src/keyboard.c: do not end window-cycling on modifier release only

If a user lets go of the modifier (e.g. alt) before the 'normal' key (e.g.
tab) when window-cycling, we do not end the cycling until both keys have
been released.  If we end the window-cycling on release of the modifier
only, some XWayland clients such as hexchat realise that tab is pressed
(even though we did not forward the event) and because we absorb the
equivalent release event it gets stuck on repeat.

Just to clarify the position here: Issue #176 describes a behaviour
whereby dmenu gets stuck on repeat after being launched with a keybind.
This patch does not resolve that issue but reflects that in Wayland, the
client is responsible for implementing "key repeat".

Changing the key repeat rate/delay in (labwc/labwc@e62bb51) was dirty fix
that need should never have been made.

include/key-state.h

@@ -6,5 +6,6 @@ void key_state_set_pressed(uint32_t keycode, bool ispressed);
 void key_state_store_pressed_keys_as_bound(void);
 bool key_state_corresponding_press_event_was_bound(uint32_t keycode);
 void key_state_bound_key_remove(uint32_t keycode);
+int key_state_nr_keys(void);
 
 #endif /* __LABWC_KEY_STATE_H */

src/key-state.c

@@ -68,3 +68,9 @@ key_state_bound_key_remove(uint32_t keycode)
 {
 	remove_key(&bound, keycode);
 }
+
+int
+key_state_nr_keys(void)
+{
+	return bound.nr_keys;
+}

src/keyboard.c

@@ -7,6 +7,8 @@
 #include "labwc.h"
 #include "workspaces.h"
 
+static bool should_cancel_cycling_on_next_key_release;
+
 static void
 change_vt(struct server *server, unsigned int vt)
 {
@@ -33,6 +35,17 @@ keyboard_any_modifiers_pressed(struct wlr_keyboard *keyboard)
 	return false;
 }
 
+static void
+end_cycling(struct server *server)
+{
+	desktop_focus_and_activate_view(&server->seat, server->osd_state.cycle_view);
+	desktop_move_to_front(server->osd_state.cycle_view);
+
+	/* osd_finish() additionally resets cycle_view to NULL */
+	osd_finish(server);
+	should_cancel_cycling_on_next_key_release = false;
+}
+
 static void
 keyboard_modifiers_notify(struct wl_listener *listener, void *data)
 {
@@ -46,12 +59,11 @@ keyboard_modifiers_notify(struct wl_listener *listener, void *data)
 		if (event->state == WL_KEYBOARD_KEY_STATE_RELEASED
 				&& !keyboard_any_modifiers_pressed(keyboard))  {
 			if (server->osd_state.cycle_view) {
-				/* end cycle */
+				if (key_state_nr_keys()) {
-				desktop_focus_and_activate_view(&server->seat,
+					should_cancel_cycling_on_next_key_release = true;
-					server->osd_state.cycle_view);
+				} else {
-				desktop_move_to_front(server->osd_state.cycle_view);
+					end_cycling(server);
-				/* osd_finish() additionally resets cycle_view to NULL */
+				}
-				osd_finish(server);
 			}
 			if (seat->workspace_osd_shown_by_modifier) {
 				workspaces_osd_hide(seat);
@@ -112,6 +124,21 @@ handle_compositor_keybindings(struct wl_listener *listener,
 	key_state_set_pressed(keycode,
 		event->state == WL_KEYBOARD_KEY_STATE_PRESSED);
 
+	/*
+	 * If a user lets go of the modifier (e.g. alt) before the 'normal' key
+	 * (e.g. tab) when window-cycling, we do not end the cycling until both
+	 * keys have been released.  If we end the window-cycling on release of
+	 * the modifier only, some XWayland clients such as hexchat realise that
+	 * tab is pressed (even though we did not forward the event) and because
+	 * we absorb the equivalent release event it gets stuck on repeat.
+	 */
+	if (should_cancel_cycling_on_next_key_release
+			&& event->state == WL_KEYBOARD_KEY_STATE_RELEASED) {
+		end_cycling(server);
+		handled = true;
+		goto out;
+	}
+
 	/*
 	 * If a press event was handled by a compositor binding, then do not
 	 * forward the corresponding release event to clients