Initial clipboard support (#237)

* WIP clipboard support code dump.

HTML5 clipboard/permissions API is a mess, so that's not an option.

* sokol_app.h: clipboard on emscripten working

* sokol_imgui.h: init-flag to disable Ctrl-hotkeys

* sokol_app.h: new sapp_consume_event() function, rename clipboard event

* add some todos to sokol_app.h

* macOS: send CLIPBOARD_PASTED event

* sokol_app.h: add Win32 clipboard support

* sokol_app.h: documentation for clipboard support

* sokol_app.h: dummy clipboard support

* Start adding clipboard support to sokol_imgui.

Current problem: on HTML5, copy/paste must happen inside JS event
handler.

* mention new sokol_app.h clipboard support in README

* readme tweaks

* sokol_app.h: MSVC warnings fixed

* sokol_imgui.h: fix key debuffering

* sokol_app.h: documentation fixes

3 files changed, 457 insertions, 21 deletions

diff --git a/README.md b/README.md
index 4c061bd1..476b6efa 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ Simple
 [STB-style](https://github.com/nothings/stb/blob/master/docs/stb_howto.txt)
 cross-platform libraries for C and C++, written in C.
 
-[See what's new](#updates) (**08-Sep-2019**: clamp-to-border texture sampling in sokol_gfx.h)
+[See what's new](#updates) (**02-Dec-2019**: initial clipboard support in sokol_app.h)
 
 [Live Samples](https://floooh.github.io/sokol-html5/index.html) via WASM.
 
@@ -465,6 +465,26 @@ Mainly some "missing features" for desktop apps:
 
 # Updates
 
+- **02-Dec-2019**: Initial clipboard support in sokol_app.h for Windows, macOS
+    and HTML5. This allows to read and write UTF-8 encoded strings from and
+    to the target platform's shared clipboard. 
+    
+    A 'real-world' example usage is in the [Visual6502 Remix project](https://github.com/floooh/v6502r).
+
+    Unfortunately clipboard support on the HTML5 platform comes with a lot of
+    platform-specific caveats which can't be solved in sokol_app.h alone
+    because of the restrictions the web platform puts on clipboard access and
+    different behaviours and support levels of the various HTML5 clipboard
+    APIs. I'm not really happy with the current HTML5 clipboard
+    implementation. It sorta works, but it sure ain't pretty :) 
+    
+    Maybe the situation will improve in a few years when all browsers agree
+    on and support the new [permission-based clipboard
+    API](https://developer.mozilla.org/en-US/docs/Web/API/Clipboard_API).
+
+    For documention of the clipboard feature, search for CLIPBOARD SUPPORT
+    in sokol_app.h
+
 - **08-Sep-2019**: sokol_gfx.h now supports clamp-to-border texture sampling:
     - the enum ```sg_wrap``` has a new member ```SG_WRAP_CLAMP_TO_BORDER```
     - there's a new enum ```sg_border_color```
diff --git a/sokol_app.h b/sokol_app.h
index ddcf2e7d..c91b7d52 100644
--- a/sokol_app.h
+++ b/sokol_app.h
@@ -101,8 +101,13 @@
     screen keyboard     | ---     | ---   | ---   | YES   | TODO    | ---   | YES
     swap interval       | YES     | YES   | YES   | YES   | TODO    | TODO  | YES
     high-dpi            | YES     | YES   | TODO  | YES   | YES     | TODO  | YES
+    clipboard           | YES     | YES   | TODO  | ---   | ---     | ---   | YES
 
-    - what about bluetooth keyboard / mouse on mobile platforms?
+    TODO
+    ====
+    - Linux clipboard support
+    - document sapp_consume_event()
+    - sapp_consume_event() on non-web platforms?
 
     STEP BY STEP
     ============
@@ -275,6 +280,58 @@
         "Really Quit?" dialog box). Note that the cleanup-callback isn't
         called on the web and mobile platforms.
 
+    CLIPBOARD SUPPORT
+    =================
+    Applications can send and receive UTF-8 encoded text data from and to the
+    system clipboard. By default, clipboard support is disabled and
+    must be enabled at startup via the following sapp_desc struct 
+    members:
+
+        sapp_desc.enable_clipboard  - set to true to enable clipboard support
+        sapp_desc.clipboard_size    - size of the internal clipboard buffer in bytes
+
+    Enabling the clipboard will dynamically allocate a clipboard buffer
+    for UTF-8 encoded text data of the requested size in bytes, the default
+    size if 8 KBytes. Strings that don't fit into the clipboard buffer
+    (including the terminating zero) will be silently clipped, so it's
+    important that you provide a big enough clipboard size for your
+    use case.
+
+    To send data to the clipboard, call sapp_set_clipboard_string() with
+    a pointer to an UTF-8 encoded, null-terminated C-string.
+
+    NOTE that on the HTML5 platform, sapp_set_clipboard_string() must be
+    called from inside a 'short-lived event handler', and there are a few
+    other HTML5-specific caveats to workaround. You'll basically have to
+    tinker until it works in all browsers :/ (maybe the situation will
+    improve when all browsers agree on and implement the new 
+    HTML5 navigator.clipboard API).
+
+    To get data from the clipboard, check for the SAPP_EVENTTYPE_CLIPBOARD_PASTED
+    event in your event handler function, and then call sapp_get_clipboard_string()
+    to obtain the updated UTF-8 encoded text.
+
+    NOTE that behaviour of sapp_get_clipboard_string() is slightly different
+    depending on platform:
+
+        - on the HTML5 platform, the internal clipboard buffer will only be updated
+          right before the SAPP_EVENTTYPE_CLIPBOARD_PASTED event is sent,
+          and sapp_get_clipboard_string() will simply return the current content
+          of the clipboard buffer
+        - on 'native' platforms, the call to sapp_get_clipboard_string() will
+          update the internal clipboard buffer with the most recent data
+          from the system clipboard
+
+    Portable code should check for the SAPP_EVENTTYPE_CLIPBOARD_PASTED event,
+    and then call sapp_get_clipboard_string() right in the event handler.
+
+    The SAPP_EVENTTYPE_CLIPBOARD_PASTED event will be generated by sokol-app
+    as follows:
+
+        - on macOS: when the Cmd+V key is pressed down
+        - on HTML5: when the browser sends a 'paste' event to the global 'window' object 
+        - on all other platforms: when the Ctrl+V key is pressed down
+
     HIGH-DPI RENDERING
     ==================
     You can set the sapp_desc.high_dpi flag during initialization to request
@@ -526,6 +583,7 @@ typedef enum sapp_event_type {
     SAPP_EVENTTYPE_RESUMED,
     SAPP_EVENTTYPE_UPDATE_CURSOR,
     SAPP_EVENTTYPE_QUIT_REQUESTED,
+    SAPP_EVENTTYPE_CLIPBOARD_PASTED,
     _SAPP_EVENTTYPE_NUM,
     _SAPP_EVENTTYPE_FORCE_U32 = 0x7FFFFFFF
 } sapp_event_type;
@@ -719,6 +777,8 @@ typedef struct sapp_desc {
     bool alpha;                         /* whether the framebuffer should have an alpha channel (ignored on some platforms) */
     const char* window_title;           /* the window title as UTF-8 encoded string */
     bool user_cursor;                   /* if true, user is expected to manage cursor image in SAPP_EVENTTYPE_UPDATE_CURSOR */
+    bool enable_clipboard;              /* enable clipboard access, default is false */
+    int clipboard_size;                 /* max size of clipboard content in bytes */
 
     const char* html5_canvas_name;      /* the name (id) of the HTML5 canvas element, default is "canvas" */
     bool html5_canvas_resize;           /* if true, the HTML5 canvas size is set to sapp_desc.width/height, otherwise canvas size is tracked */
@@ -760,8 +820,14 @@ SOKOL_API_DECL void sapp_request_quit(void);
 SOKOL_API_DECL void sapp_cancel_quit(void);
 /* intiate a "hard quit" (quit application without sending SAPP_EVENTTYPE_QUIT_REQUSTED) */
 SOKOL_API_DECL void sapp_quit(void);
+/* call from inside event callback to consume the current event (don't forward to platform) */
+SOKOL_API_DECL void sapp_consume_event(void);
 /* get the current frame counter (for comparison with sapp_event.frame_count) */
 SOKOL_API_DECL uint64_t sapp_frame_count(void);
+/* write string into clipboard */
+SOKOL_API_DECL void sapp_set_clipboard_string(const char* str);
+/* read string from clipboard (usually during SAPP_EVENTTYPE_CLIPBOARD_PASTED) */
+SOKOL_API_DECL const char* sapp_get_clipboard_string(void);
 
 /* special run-function for SOKOL_NO_ENTRY (in standard mode this is an empty stub) */
 SOKOL_API_DECL int sapp_run(const sapp_desc* desc);
@@ -933,6 +999,7 @@ typedef struct {
     bool cleanup_called;
     bool quit_requested;
     bool quit_ordered;
+    bool event_consumed;
     const char* html5_canvas_name;
     bool html5_ask_leave_site;
     char window_title[_SAPP_MAX_TITLE_LENGTH];      /* UTF-8 */
@@ -945,6 +1012,9 @@ typedef struct {
     sapp_event event;
     sapp_desc desc;
     sapp_keycode keycodes[SAPP_MAX_KEYCODES];
+    bool clipboard_enabled;
+    int clipboard_size;
+    char* clipboard;
 } _sapp_state;
 static _sapp_state _sapp;
 
@@ -994,7 +1064,7 @@ _SOKOL_PRIVATE void _sapp_call_cleanup(void) {
     }
 }
 
-_SOKOL_PRIVATE void _sapp_call_event(const sapp_event* e) {
+_SOKOL_PRIVATE bool _sapp_call_event(const sapp_event* e) {
     if (!_sapp.cleanup_called) {
         if (_sapp.desc.event_cb) {
             _sapp.desc.event_cb(e);
@@ -1003,6 +1073,13 @@ _SOKOL_PRIVATE void _sapp_call_event(const sapp_event* e) {
             _sapp.desc.event_userdata_cb(e, _sapp.desc.user_data);
         }
     }
+    if (_sapp.event_consumed) {
+        _sapp.event_consumed = false;
+        return true;
+    }
+    else {
+        return false;
+    }
 }
 
 _SOKOL_PRIVATE void _sapp_strcpy(const char* src, char* dst, int max_len) {
@@ -1034,6 +1111,11 @@ _SOKOL_PRIVATE void _sapp_init_state(const sapp_desc* desc) {
     _sapp.swap_interval = _sapp_def(_sapp.desc.swap_interval, 1);
     _sapp.html5_canvas_name = _sapp_def(_sapp.desc.html5_canvas_name, "canvas");
     _sapp.html5_ask_leave_site = _sapp.desc.html5_ask_leave_site;
+    _sapp.clipboard_enabled = _sapp.desc.enable_clipboard;
+    if (_sapp.clipboard_enabled) {
+        _sapp.clipboard_size = _sapp_def(_sapp.desc.clipboard_size, 8192);
+        _sapp.clipboard = (char*) SOKOL_CALLOC(1, _sapp.clipboard_size);
+    }
     if (_sapp.desc.window_title) {
         _sapp_strcpy(_sapp.desc.window_title, _sapp.window_title, sizeof(_sapp.window_title));
     }
@@ -1043,6 +1125,14 @@ _SOKOL_PRIVATE void _sapp_init_state(const sapp_desc* desc) {
     _sapp.dpi_scale = 1.0f;
 }
 
+_SOKOL_PRIVATE void _sapp_discard_state(void) {
+    if (_sapp.clipboard_enabled) {
+        SOKOL_ASSERT(_sapp.clipboard);
+        SOKOL_FREE((void*)_sapp.clipboard);
+    }
+    memset(&_sapp, 0, sizeof(_sapp));
+}
+
 _SOKOL_PRIVATE void _sapp_init_event(sapp_event_type type) {
     memset(&_sapp.event, 0, sizeof(_sapp.event));
     _sapp.event.type = type;
@@ -1254,6 +1344,7 @@ _SOKOL_PRIVATE void _sapp_run(const sapp_desc* desc) {
     NSApp.delegate = _sapp_macos_app_dlg_obj;
     [NSApp activateIgnoringOtherApps:YES];
     [NSApp run];
+    _sapp_discard_state();
 }
 
 /* MacOS entry function */
@@ -1592,9 +1683,10 @@ _SOKOL_PRIVATE void _sapp_macos_app_event(sapp_event_type type) {
             as a workaround, to prevent key presses from sticking we'll send
             a keyup event following right after the keydown if SUPER is also pressed
         */
-        _sapp_macos_key_event(SAPP_EVENTTYPE_KEY_DOWN, _sapp_translate_key(event.keyCode), event.isARepeat, mods);
+        const sapp_keycode key_code = _sapp_translate_key(event.keyCode);
+        _sapp_macos_key_event(SAPP_EVENTTYPE_KEY_DOWN, key_code, event.isARepeat, mods);
         if (0 != (mods & SAPP_MODIFIER_SUPER)) {
-            _sapp_macos_key_event(SAPP_EVENTTYPE_KEY_UP, _sapp_translate_key(event.keyCode), event.isARepeat, mods);
+            _sapp_macos_key_event(SAPP_EVENTTYPE_KEY_UP, key_code, event.isARepeat, mods);
         }
         const NSString* chars = event.characters;
         const NSUInteger len = chars.length;
@@ -1611,6 +1703,11 @@ _SOKOL_PRIVATE void _sapp_macos_app_event(sapp_event_type type) {
                 _sapp_call_event(&_sapp.event);
             }
         }
+        /* if this is a Cmd+V (paste), also send a CLIPBOARD_PASTE event */
+        if (_sapp.clipboard_enabled && (mods == SAPP_MODIFIER_SUPER) && (key_code == SAPP_KEYCODE_V)) {
+            _sapp_init_event(SAPP_EVENTTYPE_CLIPBOARD_PASTED);
+            _sapp_call_event(&_sapp.event);
+        }
     }
 }
 - (void)keyUp:(NSEvent*)event {
@@ -1655,6 +1752,31 @@ _SOKOL_PRIVATE void _sapp_macos_app_event(sapp_event_type type) {
 }
 @end
 
+void _sapp_macos_set_clipboard_string(const char* str) {
+    @autoreleasepool {
+        NSPasteboard* pasteboard = [NSPasteboard generalPasteboard];
+        [pasteboard declareTypes:@[NSPasteboardTypeString] owner:nil];
+        [pasteboard setString:@(str) forType:NSPasteboardTypeString];
+    }
+}
+
+const char* _sapp_macos_get_clipboard_string(void) {
+    SOKOL_ASSERT(_sapp.clipboard);
+    @autoreleasepool {
+        _sapp.clipboard[0] = 0;
+        NSPasteboard* pasteboard = [NSPasteboard generalPasteboard];
+        if (![[pasteboard types] containsObject:NSPasteboardTypeString]) {
+            return _sapp.clipboard;
+        }
+        NSString* str = [pasteboard stringForType:NSPasteboardTypeString];
+        if (!str) {
+            return _sapp.clipboard;
+        }
+        _sapp_strcpy([str UTF8String], _sapp.clipboard, _sapp.clipboard_size);
+    }
+    return _sapp.clipboard;
+}
+
 #endif /* MacOS */
 
 /*== iOS =====================================================================*/
@@ -1708,6 +1830,7 @@ _SOKOL_PRIVATE void _sapp_run(const sapp_desc* desc) {
     static int argc = 1;
     static char* argv[] = { (char*)"sokol_app" };
     UIApplicationMain(argc, argv, nil, NSStringFromClass([_sapp_app_delegate class]));
+    _sapp_discard_state();
 }
 
 /* iOS entry function */
@@ -2073,6 +2196,16 @@ EM_JS(void, sapp_js_unfocus_textfield, (void), {
     document.getElementById("_sokol_app_input_element").blur();
 });
 
+EMSCRIPTEN_KEEPALIVE void _sapp_emsc_onpaste(const char* str) {
+    if (_sapp.clipboard_enabled) {
+        _sapp_strcpy(str, _sapp.clipboard, _sapp.clipboard_size);
+        if (_sapp_events_enabled()) {
+            _sapp_init_event(SAPP_EVENTTYPE_CLIPBOARD_PASTED);
+            _sapp_call_event(&_sapp.event);
+        }
+    }
+}
+
 /*  https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onbeforeunload */
 EMSCRIPTEN_KEEPALIVE int _sapp_html5_get_ask_leave_site(void) {
     return _sapp.html5_ask_leave_site ? 1 : 0;
@@ -2087,6 +2220,35 @@ EM_JS(void, sapp_js_hook_beforeunload, (void), {
     });
 });
 
+EM_JS(void, sapp_js_init_clipboard, (void), {
+    window.addEventListener('paste', function(event) {
+        var pasted_str = event.clipboardData.getData('text');
+        ccall('_sapp_emsc_onpaste', 'void', ['string'], [pasted_str]);
+    });
+});
+
+EM_JS(void, sapp_js_write_clipboard, (const char* c_str), {
+    var str = UTF8ToString(c_str);
+    var ta = document.createElement('textarea');
+    ta.setAttribute('autocomplete', 'off');
+    ta.setAttribute('autocorrect', 'off');
+    ta.setAttribute('autocapitalize', 'off');
+    ta.setAttribute('spellcheck', 'false');
+    ta.style.left = -100 + 'px';
+    ta.style.top = -100 + 'px';
+    ta.style.height = 1;
+    ta.style.width = 1;
+    ta.value = str;
+    document.body.appendChild(ta);
+    ta.select();
+    document.execCommand('copy');
+    document.body.removeChild(ta);
+});
+
+_SOKOL_PRIVATE void _sapp_emsc_set_clipboard_string(const char* str) {
+    sapp_js_write_clipboard(str);
+}
+
 /* called from the emscripten event handler to update the keyboard visibility
     state, this must happen from an JS input event handler, otherwise
     the request will be ignored by the browser
@@ -2317,6 +2479,10 @@ _SOKOL_PRIVATE EM_BOOL _sapp_emsc_key_cb(int emsc_type, const EmscriptenKeyboard
             }
             if (type == SAPP_EVENTTYPE_CHAR) {
                 _sapp.event.char_code = emsc_event->charCode;
+                /* workaround to make Cmd+V work on Safari */
+                if ((emsc_event->metaKey) && (emsc_event->charCode == 118)) { 
+                    retval = false;
+                }
             }
             else {
                 _sapp.event.key_code = _sapp_translate_key(emsc_event->keyCode);
@@ -2397,10 +2563,15 @@ _SOKOL_PRIVATE EM_BOOL _sapp_emsc_key_cb(int emsc_type, const EmscriptenKeyboard
                         break;
                 }
             }
-            _sapp_call_event(&_sapp.event);
+            if (_sapp_call_event(&_sapp.event)) {
+                /* consume event via sapp_consume_event() */
+                retval = true;
+            }
             if (send_keyup_followup) {
                 _sapp.event.type = SAPP_EVENTTYPE_KEY_UP;
-                _sapp_call_event(&_sapp.event);
+                if (_sapp_call_event(&_sapp.event)) {
+                    retval = true;
+                }
             }
         }
     }
@@ -2567,9 +2738,16 @@ _SOKOL_PRIVATE void _sapp_emsc_init_keytable(void) {
     _sapp.keycodes[224] = SAPP_KEYCODE_LEFT_SUPER;
 }
 
+_SOKOL_PRIVATE void _sapp_emsc_init_clipboard(void) {
+    sapp_js_init_clipboard();
+}
+
 _SOKOL_PRIVATE void _sapp_run(const sapp_desc* desc) {
     _sapp_init_state(desc);
     _sapp_emsc_init_keytable();
+    if (_sapp.clipboard_enabled) {
+        _sapp_emsc_init_clipboard();
+    }
     double w, h;
     if (_sapp.desc.html5_canvas_resize) {
         w = (double) _sapp.desc.width;
@@ -2636,6 +2814,8 @@ _SOKOL_PRIVATE void _sapp_run(const sapp_desc* desc) {
     emscripten_request_animation_frame_loop(_sapp_emsc_frame, 0);
 
     sapp_js_hook_beforeunload();
+
+    // NOT A BUG: do not call _sapp_discard_state()
 }
 
 #if !defined(SOKOL_NO_ENTRY)
@@ -3894,6 +4074,12 @@ _SOKOL_PRIVATE bool _sapp_win32_utf8_to_wide(const char* src, wchar_t* dst, int
     }
 }
 
+_SOKOL_PRIVATE bool _sapp_win32_wide_to_utf8(const wchar_t* src, char* dst, int dst_num_bytes) {
+    SOKOL_ASSERT(src && dst && (dst_num_bytes > 1));
+    memset(dst, 0, dst_num_bytes);
+    return 0 != WideCharToMultiByte(CP_UTF8, 0, src, -1, dst, dst_num_bytes, NULL, NULL);
+}
+
 _SOKOL_PRIVATE void _sapp_win32_show_mouse(bool shown) {
     ShowCursor((BOOL)shown);
 }
@@ -4101,6 +4287,15 @@ _SOKOL_PRIVATE void _sapp_win32_key_event(sapp_event_type type, int vk, bool rep
         _sapp.event.key_code = _sapp.keycodes[vk];
         _sapp.event.key_repeat = repeat;
         _sapp_call_event(&_sapp.event);
+        /* check if a CLIPBOARD_PASTED event must be sent too */
+        if (_sapp.clipboard_enabled &&
+            (type == SAPP_EVENTTYPE_KEY_DOWN) && 
+            (_sapp.event.modifiers = SAPP_MODIFIER_CTRL) && 
+            (_sapp.event.key_code == SAPP_KEYCODE_V))
+        {
+            _sapp_init_event(SAPP_EVENTTYPE_CLIPBOARD_PASTED);
+            _sapp_call_event(&_sapp.event);
+        }
     }
 }
 
@@ -4352,6 +4547,69 @@ _SOKOL_PRIVATE void _sapp_win32_init_dpi(void) {
     }
 }
 
+_SOKOL_PRIVATE bool _sapp_win32_set_clipboard_string(const char* str) {
+    SOKOL_ASSERT(str);
+    SOKOL_ASSERT(_sapp_win32_hwnd);
+    SOKOL_ASSERT(_sapp.clipboard_enabled && (_sapp.clipboard_size > 0));
+
+    wchar_t* wchar_buf = 0;
+    const int wchar_buf_size = _sapp.clipboard_size * sizeof(wchar_t);
+    HANDLE object = GlobalAlloc(GMEM_MOVEABLE, wchar_buf_size);
+    if (!object) {
+        goto error;
+    }
+    wchar_buf = (wchar_t*) GlobalLock(object);
+    if (!wchar_buf) {
+        goto error;
+    }
+    if (!_sapp_win32_utf8_to_wide(str, wchar_buf, wchar_buf_size)) {
+        goto error;   
+    }
+    GlobalUnlock(wchar_buf);
+    wchar_buf = 0;
+    if (!OpenClipboard(_sapp_win32_hwnd)) {
+        goto error;
+    }
+    EmptyClipboard();
+    SetClipboardData(CF_UNICODETEXT, object);
+    CloseClipboard();
+    return true;
+
+error:
+    if (wchar_buf) {
+        GlobalUnlock(object);
+    }
+    if (object) {
+        GlobalFree(object);
+    }
+    return false;
+}
+
+_SOKOL_PRIVATE const char* _sapp_win32_get_clipboard_string(void) {
+    SOKOL_ASSERT(_sapp.clipboard_enabled && _sapp.clipboard);
+    SOKOL_ASSERT(_sapp_win32_hwnd);
+    if (!OpenClipboard(_sapp_win32_hwnd)) {
+        /* silently ignore any errors and just return the current
+           content of the local clipboard buffer
+        */
+        return _sapp.clipboard;
+    }
+    HANDLE object = GetClipboardData(CF_UNICODETEXT);
+    if (!object) {
+        CloseClipboard();
+        return _sapp.clipboard;
+    }
+    const wchar_t* wchar_buf = (const wchar_t*) GlobalLock(object);
+    if (!wchar_buf) {
+        CloseClipboard();
+        return _sapp.clipboard;
+    }
+    _sapp_win32_wide_to_utf8(wchar_buf, _sapp.clipboard, _sapp.clipboard_size);
+    GlobalUnlock(object);
+    CloseClipboard();
+    return _sapp.clipboard;
+}
+
 _SOKOL_PRIVATE void _sapp_run(const sapp_desc* desc) {
     _sapp_init_state(desc);
     _sapp_win32_init_keytable();
@@ -4416,6 +4674,7 @@ _SOKOL_PRIVATE void _sapp_run(const sapp_desc* desc) {
         _sapp_wgl_shutdown();
     #endif
     _sapp_win32_destroy_window();
+    _sapp_discard_state();
 }
 
 static char** _sapp_win32_command_line_to_utf8_argv(LPWSTR w_command_line, int* o_argc) {
@@ -5191,6 +5450,8 @@ void ANativeActivity_onCreate(ANativeActivity* activity, void* saved_state, size
     activity->callbacks->onLowMemory = _sapp_android_on_low_memory;
 
     SOKOL_LOG("NativeActivity successfully created");
+
+    /* NOT A BUG: do NOT call sapp_discard_state() */
 }
 
 #endif /* Android */
@@ -6673,6 +6934,15 @@ _SOKOL_PRIVATE void _sapp_x11_key_event(sapp_event_type type, sapp_keycode key,
         _sapp.event.key_repeat = repeat;
         _sapp.event.modifiers = mods;
         _sapp_call_event(&_sapp.event);
+        /* check if a CLIPBOARD_PASTED event must be sent too */
+        if (_sapp.clipboard_enabled && 
+            (type == SAPP_EVENTTYPE_KEY_DOWN) && 
+            (_sapp.event.modifiers = SAPP_MODIFIER_CTRL) && 
+            (_sapp.event.key_code == SAPP_KEYCODE_V))
+        {
+            _sapp_init_event(SAPP_EVENTTYPE_CLIPBOARD_PASTED);
+            _sapp_call_event(&_sapp.event);
+        }
     }
 }
 
@@ -7019,6 +7289,7 @@ _SOKOL_PRIVATE void _sapp_run(const sapp_desc* desc) {
     _sapp_glx_destroy_context();
     _sapp_x11_destroy_window();
     XCloseDisplay(_sapp_x11_display);
+    _sapp_discard_state();
 }
 
 #if !defined(SOKOL_NO_ENTRY)
@@ -7134,6 +7405,44 @@ SOKOL_API_IMPL void sapp_quit(void) {
     _sapp.quit_ordered = true;
 }
 
+SOKOL_API_IMPL void sapp_consume_event(void) {
+    _sapp.event_consumed = true;
+}
+
+/* NOTE: on HTML5, sapp_set_clipboard_string() must be called from within event handler! */
+SOKOL_API_IMPL void sapp_set_clipboard_string(const char* str) {
+    if (!_sapp.clipboard_enabled) {
+        return;
+    }
+    SOKOL_ASSERT(str);
+    #if defined(__APPLE__) && defined(TARGET_OS_IPHONE) && !TARGET_OS_IPHONE
+        _sapp_macos_set_clipboard_string(str);
+    #elif defined(__EMSCRIPTEN__)
+        _sapp_emsc_set_clipboard_string(str);
+    #elif defined(_WIN32)
+        _sapp_win32_set_clipboard_string(str);
+    #else
+        /* not implemented */
+    #endif
+    _sapp_strcpy(str, _sapp.clipboard, _sapp.clipboard_size);
+}
+
+SOKOL_API_IMPL const char* sapp_get_clipboard_string(void) {
+    if (!_sapp.clipboard_enabled) {
+        return "";
+    }
+    #if defined(__APPLE__) && defined(TARGET_OS_IPHONE) && !TARGET_OS_IPHONE
+        return _sapp_macos_get_clipboard_string();
+    #elif defined(__EMSCRIPTEN__)
+        return _sapp.clipboard;
+    #elif defined(_WIN32)
+        return _sapp_win32_get_clipboard_string();
+    #else
+        /* not implemented */
+        return _sapp.clipboard;
+    #endif
+}
+
 SOKOL_API_IMPL const void* sapp_metal_get_device(void) {
     SOKOL_ASSERT(_sapp.valid);
     #if defined(SOKOL_METAL)
diff --git a/util/sokol_imgui.h b/util/sokol_imgui.h
index 7e796172..d8b3d8c7 100644
--- a/util/sokol_imgui.h
+++ b/util/sokol_imgui.h
@@ -219,6 +219,7 @@ typedef struct simgui_desc_t {
     float dpi_scale;
     const char* ini_filename;
     bool no_default_font;
+    bool disable_hotkeys;   /* don't let ImGui handle Ctrl-A,C,V,X,Y,Z */
 } simgui_desc_t;
 
 SOKOL_API_DECL void simgui_setup(const simgui_desc_t* desc);
@@ -251,6 +252,10 @@ SOKOL_API_DECL void simgui_shutdown(void);
 #include <stddef.h> /* offsetof */
 #include <string.h> /* memset */
 
+#if !defined(SOKOL_IMGUI_NO_SOKOL_APP) && defined(__EMSCRIPTEN__)
+#include <emscripten.h>
+#endif
+
 #ifndef SOKOL_API_IMPL
 #define SOKOL_API_IMPL
 #endif
@@ -278,6 +283,8 @@ typedef struct {
     ImVec2 disp_size;
 } _simgui_vs_params_t;
 
+#define SIMGUI_MAX_KEY_VALUE (512)      // same as ImGuis IO.KeysDown array
+
 typedef struct {
     simgui_desc_t desc;
     sg_buffer vbuf;
@@ -288,6 +295,9 @@ typedef struct {
     #if !defined(SOKOL_IMGUI_NO_SOKOL_APP)
     bool btn_down[SAPP_MAX_MOUSEBUTTONS];
     bool btn_up[SAPP_MAX_MOUSEBUTTONS];
+    uint8_t keys_down[SIMGUI_MAX_KEY_VALUE];     // bits 0..3 or modifiers, != 0 is key-down
+    uint8_t keys_up[SIMGUI_MAX_KEY_VALUE];       // same is keys_down
+    bool is_osx;                // return true if running on OSX (or HTML5 OSX), needed for copy/paste
     #endif
 } _simgui_state_t;
 static _simgui_state_t _simgui;
@@ -701,12 +711,46 @@ static const uint8_t _simgui_fs_bin[] = {
 #error "sokol_imgui.h: No sokol_gfx.h backend selected (SOKOL_GLCORE33, SOKOL_GLES2, SOKOL_GLES3, SOKOL_D3D11 or SOKOL_METAL)"
 #endif
 
+#if !defined(SOKOL_IMGUI_NO_SOKOL_APP)
+static void _simgui_set_clipboard(void* user_data, const char* text) {
+    sapp_set_clipboard_string(text);
+}
+
+static const char* _simgui_get_clipboard(void* user_data) {
+    return sapp_get_clipboard_string();
+}
+
+#if defined(__EMSCRIPTEN__)
+EM_JS(int, simgui_js_is_osx, (void), {
+    if (navigator.userAgent.includes('Macintosh')) {
+        return 1;
+    }
+    else {
+        return 0;
+    }
+});
+#endif
+
+static bool _simgui_is_osx(void) {
+    #if defined(__EMSCRIPTEN__)
+    return simgui_js_is_osx();
+    #elif defined(__APPLE__)
+    return true;
+    #else
+    return false;
+    #endif
+}
+#endif
+
 SOKOL_API_IMPL void simgui_setup(const simgui_desc_t* desc) {
     SOKOL_ASSERT(desc);
     memset(&_simgui, 0, sizeof(_simgui));
     _simgui.desc = *desc;
     _simgui.desc.max_vertices = _simgui_def(_simgui.desc.max_vertices, 65536);
     _simgui.desc.dpi_scale = _simgui_def(_simgui.desc.dpi_scale, 1.0f);
+    #if !defined(SOKOL_IMGUI_NO_SOKOL_APP)
+    _simgui.is_osx = _simgui_is_osx();
+    #endif
     /* can keep color_format, depth_format and sample_count as is,
        since sokol_gfx.h will do its own default-value handling
     */
@@ -728,6 +772,7 @@ SOKOL_API_IMPL void simgui_setup(const simgui_desc_t* desc) {
         }
     #endif
     io->IniFilename = _simgui.desc.ini_filename;
+    io->ConfigMacOSXBehaviors = _simgui_is_osx();
     io->BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;
     #if !defined(SOKOL_IMGUI_NO_SOKOL_APP)
         io->KeyMap[ImGuiKey_Tab] = SAPP_KEYCODE_TAB;
@@ -744,12 +789,18 @@ SOKOL_API_IMPL void simgui_setup(const simgui_desc_t* desc) {
         io->KeyMap[ImGuiKey_Space] = SAPP_KEYCODE_SPACE;
         io->KeyMap[ImGuiKey_Enter] = SAPP_KEYCODE_ENTER;
         io->KeyMap[ImGuiKey_Escape] = SAPP_KEYCODE_ESCAPE;
-        io->KeyMap[ImGuiKey_A] = SAPP_KEYCODE_A;
-        io->KeyMap[ImGuiKey_C] = SAPP_KEYCODE_C;
-        io->KeyMap[ImGuiKey_V] = SAPP_KEYCODE_V;
-        io->KeyMap[ImGuiKey_X] = SAPP_KEYCODE_X;
-        io->KeyMap[ImGuiKey_Y] = SAPP_KEYCODE_Y;
-        io->KeyMap[ImGuiKey_Z] = SAPP_KEYCODE_Z;
+        if (!_simgui.desc.disable_hotkeys) {
+            io->KeyMap[ImGuiKey_A] = SAPP_KEYCODE_A;
+            io->KeyMap[ImGuiKey_C] = SAPP_KEYCODE_C;
+            io->KeyMap[ImGuiKey_V] = SAPP_KEYCODE_V;
+            io->KeyMap[ImGuiKey_X] = SAPP_KEYCODE_X;
+            io->KeyMap[ImGuiKey_Y] = SAPP_KEYCODE_Y;
+            io->KeyMap[ImGuiKey_Z] = SAPP_KEYCODE_Z;
+        }
+        #if !defined(SOKOL_IMGUI_NO_SOKOL_APP)
+        io->SetClipboardTextFn = _simgui_set_clipboard;
+        io->GetClipboardTextFn = _simgui_get_clipboard;
+        #endif
     #endif
 
     /* create sokol-gfx resources */
@@ -872,6 +923,13 @@ SOKOL_API_IMPL void simgui_shutdown(void) {
     sg_destroy_buffer(_simgui.vbuf);
 }
 
+_SOKOL_PRIVATE void _simgui_set_imgui_modifiers(ImGuiIO* io, uint8_t mods) {
+    io->KeyAlt = (mods & SAPP_MODIFIER_ALT) != 0;
+    io->KeyCtrl = (mods & SAPP_MODIFIER_CTRL) != 0;
+    io->KeyShift = (mods & SAPP_MODIFIER_SHIFT) != 0;
+    io->KeySuper = (mods & SAPP_MODIFIER_SUPER) != 0;
+}
+
 SOKOL_API_IMPL void simgui_new_frame(int width, int height, double delta_time) {
     #if defined(__cplusplus)
         ImGuiIO* io = &ImGui::GetIO();
@@ -892,6 +950,18 @@ SOKOL_API_IMPL void simgui_new_frame(int width, int height, double delta_time) {
             io->MouseDown[i] = false;
         }
     }
+    for (int i = 0; i < SIMGUI_MAX_KEY_VALUE; i++) {
+        if (_simgui.keys_down[i]) {
+            io->KeysDown[i] = true;
+            _simgui_set_imgui_modifiers(io, _simgui.keys_down[i]);
+            _simgui.keys_down[i] = 0;
+        }
+        else if (_simgui.keys_up[i]) {
+            io->KeysDown[i] = false;
+            _simgui_set_imgui_modifiers(io, _simgui.keys_up[i]);
+            _simgui.keys_up[i] = 0;
+        }
+    }
     if (io->WantTextInput && !sapp_keyboard_shown()) {
         sapp_show_keyboard(true);
     }
@@ -1009,6 +1079,15 @@ SOKOL_API_IMPL void simgui_render(void) {
 }
 
 #if !defined(SOKOL_IMGUI_NO_SOKOL_APP)
+_SOKOL_PRIVATE bool _simgui_is_ctrl(uint8_t modifiers) {
+    if (_simgui.is_osx) {
+        return 0 != (modifiers & SAPP_MODIFIER_SUPER);
+    }
+    else {
+        return 0 != (modifiers & SAPP_MODIFIER_CTRL);
+    }
+}
+
 SOKOL_API_IMPL bool simgui_handle_event(const sapp_event* ev) {
     const float dpi_scale = _simgui.desc.dpi_scale;
     #if defined(__cplusplus)
@@ -1016,10 +1095,7 @@ SOKOL_API_IMPL bool simgui_handle_event(const sapp_event* ev) {
     #else
         ImGuiIO* io = igGetIO();
     #endif
-    io->KeyAlt = (ev->modifiers & SAPP_MODIFIER_ALT) != 0;
-    io->KeyCtrl = (ev->modifiers & SAPP_MODIFIER_CTRL) != 0;
-    io->KeyShift = (ev->modifiers & SAPP_MODIFIER_SHIFT) != 0;
-    io->KeySuper = (ev->modifiers & SAPP_MODIFIER_SUPER) != 0;
+    _simgui_set_imgui_modifiers(io, ev->modifiers);
     switch (ev->type) {
         case SAPP_EVENTTYPE_MOUSE_DOWN:
             io->MousePos.x = ev->mouse_x / dpi_scale;
@@ -1069,17 +1145,43 @@ SOKOL_API_IMPL bool simgui_handle_event(const sapp_event* ev) {
             _simgui.btn_up[0] = _simgui.btn_down[0] = false;
             break;
         case SAPP_EVENTTYPE_KEY_DOWN:
-            io->KeysDown[ev->key_code] = true;
+            /* intercept Ctrl-V, this is handled via EVENTTYPE_CLIPBOARD_PASTED */
+            if (_simgui_is_ctrl(ev->modifiers) && (ev->key_code == SAPP_KEYCODE_V)) {
+                break;
+            }
+            /* on web platform, don't forward Ctrl-X, Ctrl-V to the browser */
+            if (_simgui_is_ctrl(ev->modifiers) && (ev->key_code == SAPP_KEYCODE_X)) {
+                sapp_consume_event();
+            }
+            if (_simgui_is_ctrl(ev->modifiers) && (ev->key_code == SAPP_KEYCODE_C)) {
+                sapp_consume_event();
+            }
+            _simgui.keys_down[ev->key_code] = 0x80 | ev->modifiers;
             break;
         case SAPP_EVENTTYPE_KEY_UP:
-            io->KeysDown[ev->key_code] = false;
+            /* intercept Ctrl-V, this is handled via EVENTTYPE_CLIPBOARD_PASTED */
+            if (_simgui_is_ctrl(ev->modifiers) && (ev->key_code == SAPP_KEYCODE_V)) {
+                break;
+            }
+            /* on web platform, don't forward Ctrl-X, Ctrl-V to the browser */
+            if (_simgui_is_ctrl(ev->modifiers) && (ev->key_code == SAPP_KEYCODE_X)) {
+                sapp_consume_event();
+            }
+            if (_simgui_is_ctrl(ev->modifiers) && (ev->key_code == SAPP_KEYCODE_C)) {
+                sapp_consume_event();
+            }
+            _simgui.keys_up[ev->key_code] = 0x80 | ev->modifiers;
             break;
         case SAPP_EVENTTYPE_CHAR:
             /* on some platforms, special keys may be reported as
                characters, which may confuse some ImGui widgets,
-               drop those
+               drop those, also don't forward characters if some
+               modifiers have been pressed
             */
-            if ((ev->char_code >= 32) && (ev->char_code != 127)) {
+            if ((ev->char_code >= 32) &&
+                (ev->char_code != 127) &&
+                (0 == (ev->modifiers & (SAPP_MODIFIER_ALT|SAPP_MODIFIER_CTRL|SAPP_MODIFIER_SUPER))))
+            {
                 #if defined(__cplusplus)
                     io->AddInputCharacter((ImWchar)ev->char_code);
                 #else
@@ -1087,6 +1189,11 @@ SOKOL_API_IMPL bool simgui_handle_event(const sapp_event* ev) {
                 #endif
             }
             break;
+        case SAPP_EVENTTYPE_CLIPBOARD_PASTED:
+            /* simulate a Ctrl-V key down/up */
+            _simgui.keys_down[SAPP_KEYCODE_V] = _simgui.keys_up[SAPP_KEYCODE_V] =
+                0x80 | (_simgui.is_osx ? SAPP_MODIFIER_SUPER:SAPP_MODIFIER_CTRL);
+            break;
         default:
             break;
     }