Fixed mouse event forwarding in macos example (#2710, #1961)

docs/CHANGELOG.txt

@@ -77,6 +77,8 @@ Other Changes:
 - Backends: Vulkan: Added support for specifying multisample count.
   Set ImGui_ImplVulkan_InitInfo::MSAASamples to one of the VkSampleCountFlagBits values
   to use, default is non-multisampled as before. (#2705, #2706) [@vilya]
+- Examples: OSX: Fix example_apple_opengl2/main.mm not forwarding mouse clicks and drags correctly. (#1961, #2710)
+  [@intonarumori, @ElectricMagic]
 - Misc: Updated stb_rect_pack from 0.99 to 1.00 (fixes by @rygorous: off-by-1 bug in best-fit heuristic,
   fix handling of rectangles too large to fit inside texture). (#2762) [@tido64]
 

examples/example_apple_opengl2/main.mm

@@ -133,12 +133,6 @@
     return (YES);
 }
 
-// Flip coordinate system upside down on Y
--(BOOL)isFlipped
-{
-    return (YES);
-}
-
 -(void)dealloc
 {
     animationTimer = nil;
@@ -150,6 +144,8 @@
 -(void)flagsChanged:(NSEvent *)event    { ImGui_ImplOSX_HandleEvent(event, self); }
 -(void)mouseDown:(NSEvent *)event       { ImGui_ImplOSX_HandleEvent(event, self); }
 -(void)mouseUp:(NSEvent *)event         { ImGui_ImplOSX_HandleEvent(event, self); }
+-(void)mouseMoved:(NSEvent *)event      { ImGui_ImplOSX_HandleEvent(event, self); }
+-(void)mouseDragged:(NSEvent *)event    { ImGui_ImplOSX_HandleEvent(event, self); }
 -(void)scrollWheel:(NSEvent *)event     { ImGui_ImplOSX_HandleEvent(event, self); }
 
 @end
@@ -179,6 +175,7 @@
 
     _window = [[NSWindow alloc] initWithContentRect:viewRect styleMask:NSWindowStyleMaskTitled|NSWindowStyleMaskMiniaturizable|NSWindowStyleMaskResizable|NSWindowStyleMaskClosable backing:NSBackingStoreBuffered defer:YES];
     [_window setTitle:@"Dear ImGui OSX+OpenGL2 Example"];
+    [_window setAcceptsMouseMovedEvents:YES];
     [_window setOpaque:YES];
     [_window makeKeyAndOrderFront:NSApp];