Modifier keys remain in pressed state after triggering screen snipping function

[jhauberg]

OS: MacOS 10.12.4
GLFW Version: GLFW 3.3.0 Cocoa NSGL

When I trigger the MacOS screen snipping function (shift-cmd-4 or shift-cmd-4+space), then glfwGetKey(window, GLFW_KEY_LEFT_SHIFT) and glfwGetKey(window, GLFW_KEY_LEFT_SUPER) will continuously report GLFW_PRESS each frame.

I've found two ways to reset the key state:

1. Pressing each key once
2. Having the window lose and then regain focus (it's not enough just clicking the window- it likely already has focus)

[dmitshur]

Do you know if that happens only when doing a screenshot, or does it also happen if the window loses focus in any other way?

[jhauberg]

I can't think of a way to make it lose focus and get back to the window without letting it regain focus (which fixes said issue)...
Also note that the fullscreen screenshot function (shift-cmd-3) does not cause any problems.

[bear24rw]

Before the screenshot is taken flagsChanged is called once for each modifier key as they are being pressed in sequence by the user preforming the screenshot chord, then after the screenshot is taken flagsChanged gets called once but the key is a and the mods are cleared out. We then only call _glfwInputKey once, we probably should be calling it for each mod key so that they can get marked as released?

[bear24rw]

So I "fixed" it with this insanely ugly patch but I'm not sure a better way to do this other than just emit events for every modifier every time.

diff --git a/src/cocoa_window.m b/src/cocoa_window.m
index 6f8aa978..0ea3209c 100644
--- a/src/cocoa_window.m
+++ b/src/cocoa_window.m
@@ -586,6 +586,15 @@ static const NSRange kEmptyRange = { NSNotFound, 0 };
         action = GLFW_RELEASE;

     _glfwInputKey(window, key, [event keyCode], action, mods);
+
+    _glfwInputKey(window, GLFW_KEY_LEFT_SHIFT   , _glfw.ns.scancodes[GLFW_KEY_LEFT_SHIFT   ], mods & GLFW_MOD_SHIFT   ? GLFW_PRESS : GLFW_RELEASE, mods);
+    _glfwInputKey(window, GLFW_KEY_LEFT_CONTROL , _glfw.ns.scancodes[GLFW_KEY_LEFT_CONTROL ], mods & GLFW_MOD_CONTROL ? GLFW_PRESS : GLFW_RELEASE, mods);
+    _glfwInputKey(window, GLFW_KEY_LEFT_ALT     , _glfw.ns.scancodes[GLFW_KEY_LEFT_ALT     ], mods & GLFW_MOD_ALT     ? GLFW_PRESS : GLFW_RELEASE, mods);
+    _glfwInputKey(window, GLFW_KEY_LEFT_SUPER   , _glfw.ns.scancodes[GLFW_KEY_LEFT_SUPER   ], mods & GLFW_MOD_SUPER   ? GLFW_PRESS : GLFW_RELEASE, mods);
+    _glfwInputKey(window, GLFW_KEY_RIGHT_SHIFT  , _glfw.ns.scancodes[GLFW_KEY_RIGHT_SHIFT  ], mods & GLFW_MOD_SHIFT   ? GLFW_PRESS : GLFW_RELEASE, mods);
+    _glfwInputKey(window, GLFW_KEY_RIGHT_CONTROL, _glfw.ns.scancodes[GLFW_KEY_RIGHT_CONTROL], mods & GLFW_MOD_CONTROL ? GLFW_PRESS : GLFW_RELEASE, mods);
+    _glfwInputKey(window, GLFW_KEY_RIGHT_ALT    , _glfw.ns.scancodes[GLFW_KEY_RIGHT_ALT    ], mods & GLFW_MOD_ALT     ? GLFW_PRESS : GLFW_RELEASE, mods);
+    _glfwInputKey(window, GLFW_KEY_RIGHT_SUPER  , _glfw.ns.scancodes[GLFW_KEY_RIGHT_SUPER  ], mods & GLFW_MOD_SUPER   ? GLFW_PRESS : GLFW_RELEASE, mods);
 }

 - (void)keyUp:(NSEvent *)event

flagsChanged.patch