hw/xwin: Restore modifier key state when an X window gains focus

In multiwindow mode, the state of the modifier keys was lost when a window is
created (or raised) and focus moved to that window.

For example: In window A Ctrl + some key opens a window B, then in window B Ctrl
+ some other key triggers the next action. However after the opening of window B
the Ctrl key has to be released and pressed again. If the user keeps the Ctrl
key held down when the window B is opened, the next key press X will be
interpreted as X and not as Ctrl+X.

Extended the function winRestoreModeKeyStates in winkeybd.c to consider not only
the mode switch key but also the modifiers Ctrl, Shift, Alt/AltGr by using the
Windows function GetAsyncKeyState.

A combined Ctrl+AltGr modifier state cannot be restored correctly, as Windows
always fakes a Ctrl-L when AltGr is pressed.

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>

1 files changed, 23 insertions, 0 deletions

diff --git a/hw/xwin/winkeybd.c b/hw/xwin/winkeybd.c
index 278342f72..f1add8912 100644
--- a/hw/xwin/winkeybd.c
+++ b/hw/xwin/winkeybd.c
@@ -283,6 +283,29 @@ winRestoreModeKeyStates (void)
    * have a logical XOR operator, so we use a macro instead.
    */
 
+  {
+    /* consider modifer keys */
+
+    BOOL ctrl   = (GetAsyncKeyState (VK_CONTROL) < 0);
+    BOOL shift  = (GetAsyncKeyState (VK_SHIFT)   < 0);
+    BOOL alt    = (GetAsyncKeyState (VK_LMENU)   < 0);
+    BOOL altgr  = (GetAsyncKeyState (VK_RMENU)   < 0);
+
+    if (ctrl && altgr) ctrl = FALSE;
+
+    if (WIN_XOR (internalKeyStates & ControlMask, ctrl))
+      winSendKeyEvent (KEY_LCtrl, ctrl);
+
+    if (WIN_XOR (internalKeyStates & ShiftMask, shift))
+      winSendKeyEvent (KEY_ShiftL, shift);
+
+    if (WIN_XOR (internalKeyStates & Mod1Mask, alt))
+      winSendKeyEvent (KEY_Alt, alt);
+
+    if (WIN_XOR (internalKeyStates & Mod5Mask, altgr))
+      winSendKeyEvent (KEY_AltLang, altgr);
+  }
+
   /* Has the key state changed? */
   dwKeyState = GetKeyState (VK_NUMLOCK) & 0x0001;
   if (WIN_XOR (internalKeyStates & NumLockMask, dwKeyState))