gdk-win32: Send fake release key event for shift key

Windows does not send any release key event for one of the shift keys
when both shift keys were pressed together. This commit solves
the problem by sending the extra release key event for the shift key
which was released as first, when the other shift key is released.

Other modifiers (e.g. Ctrl, Alt) do not have this problem.

https://bugzilla.gnome.org/show_bug.cgi?id=751721

1 files changed, 34 insertions, 0 deletions

diff --git a/gdk/win32/gdkevents-win32.c b/gdk/win32/gdkevents-win32.c
index eed1bc6e5d..82e9368fd5 100644
--- a/gdk/win32/gdkevents-win32.c
+++ b/gdk/win32/gdkevents-win32.c
@@ -136,6 +136,8 @@ static UINT     sync_timer = 0;
 
 static int debug_indent = 0;
 
+static int both_shift_pressed[2]; /* to store keycodes for shift keys */
+
 static void
 assign_object (gpointer lhsp,
 	       gpointer rhs)
@@ -2110,6 +2112,38 @@ gdk_event_translate (MSG  *msg,
 
       fill_key_event_string (event);
 
+  /* Only one release key event is fired when both shift keys are pressed together
+     and then released. In order to send the missing event, press events for shift
+     keys are recorded and sent together when the release event occurs.
+     Other modifiers (e.g. ctrl, alt) don't have this problem. */
+  if (msg->message == WM_KEYDOWN && msg->wParam == VK_SHIFT)
+    {
+      int pressed_shift = msg->lParam & 0xffffff; /* mask shift modifier */
+      if (both_shift_pressed[0] == 0)
+        both_shift_pressed[0] = pressed_shift;
+      else if (both_shift_pressed[0] != pressed_shift)
+        both_shift_pressed[1] = pressed_shift;
+    }
+
+  if (msg->message == WM_KEYUP && msg->wParam == VK_SHIFT)
+    {
+      if (both_shift_pressed[0] != 0 && both_shift_pressed[1] != 0)
+        {
+          gint tmp_retval;
+          MSG fake_release = *msg;
+          int pressed_shift = msg->lParam & 0xffffff;
+
+          if (both_shift_pressed[0] == pressed_shift)
+            fake_release.lParam = both_shift_pressed[1];
+          else
+            fake_release.lParam = both_shift_pressed[0];
+
+          both_shift_pressed[0] = both_shift_pressed[1] = 0;
+          gdk_event_translate (&fake_release, &tmp_retval);
+        }
+      both_shift_pressed[0] = both_shift_pressed[1] = 0;
+    }
+
       /* Reset MOD1_MASK if it is the Alt key itself */
       if (msg->wParam == VK_MENU)
 	event->key.state &= ~GDK_MOD1_MASK;