Give windows focus before sending events

Events from the GUI daemon are directed at specific windows.  Ensuring
that they are sent to the correct window is more importent than obeying
the ICCCM input hint.  Giving pointer focus to a window is accomplished
by raising it.

Fixes QubesOS/qubes-issues#3267.

Author: DemiMarie

gui-agent/vmside.c

@@ -1600,11 +1600,17 @@ static void mkghandles(Ghandles * g)
     g->clipboard_data_len = 0;
 }
 
-static void handle_keypress(Ghandles * g, XID UNUSED(winid))
+static void handle_keypress(Ghandles * g, XID winid)
 {
     struct msg_keypress key;
     XkbStateRec state;
     read_data(g->vchan, (char *) &key, sizeof(key));
+
+    // Ignore the input hint.  If the window already has focus, then this is a
+    // no-op other than changing a timestamp.  Otherwise, it is too late to wait
+    // for the window to take focus for itself.
+    XSetInputFocus(g->display, winid, RevertToParent, g->time);
+
     // sync modifiers state
     if (XkbGetState(g->display, XkbUseCoreKbd, &state) != Success) {
         if (g->log_level > 0)
@@ -1673,8 +1679,9 @@ static void handle_button(Ghandles * g, XID winid)
     if (l && l->data && ((struct window_data*)l->data)->is_docked) {
         /* get position of embeder, not icon itself*/
         winid = ((struct window_data*)l->data)->embeder;
-        XRaiseWindow(g->display, winid);
     }
+    /* If the window was not raised before, it sure is now! */
+    XRaiseWindow(g->display, winid);
 
     if (g->log_level > 1)
         fprintf(stderr,
@@ -1790,26 +1797,25 @@ static void take_focus(Ghandles * g, XID winid)
 static void handle_focus(Ghandles * g, XID winid)
 {
     struct msg_focus key;
-    struct genlist *l;
-    int input_hint;
-    int use_take_focus;
-
+    bool input_hint = true, use_take_focus = false, is_docked = false;
+    Window embedder = None;
+    struct genlist *l = list_lookup(windows_list, winid);
+    if (l && l->data) {
+        const struct window_data *data = l->data;
+        input_hint = data->input_hint;
+        use_take_focus = data->support_take_focus;
+        if ((is_docked = data->is_docked))
+            embedder = data->embeder;
+    } else {
+        fprintf(stderr, "WARNING handle_focus: Window 0x%x data not initialized", (int)winid);
+    }
     read_data(g->vchan, (char *) &key, sizeof(key));
     if (key.type == FocusIn
             && (key.mode == NotifyNormal || key.mode == NotifyUngrab)) {
 
         XRaiseWindow(g->display, winid);
-
-        if ( (l=list_lookup(windows_list, winid)) && (l->data) ) {
-            input_hint = ((struct window_data*)l->data)->input_hint;
-            use_take_focus = ((struct window_data*)l->data)->support_take_focus;
-            if (((struct window_data*)l->data)->is_docked)
-                XRaiseWindow(g->display, ((struct window_data*)l->data)->embeder);
-        } else {
-            fprintf(stderr, "WARNING handle_focus: Window 0x%x data not initialized", (int)winid);
-            input_hint = True;
-            use_take_focus = False;
-        }
+        if (is_docked)
+            XRaiseWindow(g->display, embedder);
 
         // Give input focus only to window that set the input hint
         if (input_hint)
@@ -1824,12 +1830,6 @@ static void handle_focus(Ghandles * g, XID winid)
     } else if (key.type == FocusOut
             && (key.mode == NotifyNormal
                 || key.mode == NotifyUngrab)) {
-        if ( (l=list_lookup(windows_list, winid)) && (l->data) )
-            input_hint = ((struct window_data*)l->data)->input_hint;
-        else {
-            fprintf(stderr, "WARNING handle_focus: Window 0x%x data not initialized", (int)winid);
-            input_hint = True;
-        }
         if (input_hint)
             XSetInputFocus(g->display, None, RevertToParent, g->time);