Window loosing or gaining focus must reset the keys.

src/windy/internal.nim

@@ -151,6 +151,11 @@ template handleButtonReleaseTemplate*() =
   if window.onButtonRelease != nil:
     window.onButtonRelease(button)
 
+template clearButtonsTemplate*() =
+  let buttons = window.state.buttonDown
+  for button in buttons:
+    window.handleButtonRelease(button)
+
 template handleRuneTemplate*() =
   if not window.state.runeInputEnabled:
     return

src/windy/platforms/macos/platform.nim

@@ -326,6 +326,7 @@ proc windowDidMove(
   if window != nil and window.onMove != nil:
     window.onMove()
 
+
 proc canBecomeKeyWindow(
   self: ID,
   cmd: SEL,
@@ -341,6 +342,7 @@ proc windowDidBecomeKey(
   let window = windows.forNSWindow(self.NSWindow)
   if window == nil:
     return
+  clearButtonsTemplate()
   if window.onFocusChange != nil:
     window.onFocusChange()
   handleMouseMove(window, window.inner.mouseLocationOutsideOfEventStream)
@@ -351,7 +353,10 @@ proc windowDidResignKey(
   notification: NSNotification
 ): ID {.cdecl.} =
   let window = windows.forNSWindow(self.NSWindow)
-  if window != nil and window.onFocusChange != nil:
+  if window == nil:
+    return
+  clearButtonsTemplate()
+  if window.onFocusChange != nil:
     window.onFocusChange()
   # When loosing focus, prev mouse position is not valid.
   window.state.hasPrevMouse = false

src/windy/platforms/win32/platform.nim

@@ -253,7 +253,7 @@ proc destroy(window: Window) =
   window.onButtonRelease = nil
   window.onRune = nil
   window.onImeChange = nil
-  
+
   # Destroy graphics context
   window.destoryGraphicsContext()
 
@@ -889,6 +889,7 @@ proc wndProc(
       window.onFrame()
     return 0
   of WM_SETFOCUS, WM_KILLFOCUS:
+    clearButtonsTemplate()
     if window.onFocusChange != nil:
       window.onFocusChange()
     return 0
@@ -1068,10 +1069,10 @@ when Backend == OpenGLBackend:
 
 
   proc createGraphicsContext(
-    window: Window, 
-    depthBits: int, 
+    window: Window,
+    depthBits: int,
     stencilBits: int,
-     msaa: MSAA, 
+     msaa: MSAA,
      vsync: bool,
      openglVersion: OpenGLVersion
   ) =
@@ -1167,10 +1168,10 @@ elif Backend == DirectXBackend:
     discard
 
   proc createGraphicsContext(
-    window: Window, 
-    depthBits: int, 
-    stencilBits: int, 
-    msaa: MSAA, 
+    window: Window,
+    depthBits: int,
+    stencilBits: int,
+    msaa: MSAA,
     vsync: bool,
     openglVersion: OpenGLVersion
   ) =
@@ -1231,7 +1232,7 @@ proc newWindow*(
 
     result.style = style
     result.visible = visible
-    
+
 
   except WindyError as e:
     destroy result

tests/manual_alt_tab.nim

@@ -0,0 +1,29 @@
+import opengl, os, windy
+
+let window = newWindow("Windy Callbacks", ivec2(1280, 800))
+window.runeInputEnabled = true
+
+window.makeContextCurrent()
+loadExtensions()
+
+window.onFrame = proc() =
+  glClear(GL_COLOR_BUFFER_BIT)
+
+  # Print if alt is down, when mouse is down:
+  if window.buttonDown[KeyLeftSuper] or
+    window.buttonDown[KeyRightSuper] or
+    window.buttonDown[KeyLeftAlt] or
+    window.buttonDown[KeyRightAlt] or
+    window.buttonDown[KeyLeftControl] or
+    window.buttonDown[KeyRightControl]:
+      glClearColor(1.0f, 0.0f, 0.0f, 1.0f)
+  else:
+    glClearColor(0.0f, 0.0f, 0.0f, 1.0f)
+
+  window.swapBuffers()
+
+while not window.closeRequested:
+
+  if window.minimized or not window.visible:
+    sleep(10)
+  pollEvents()