cursor: fix button release events sometimes not being sent

When `wlr_seat_pointer_notify_button()` is called on a button press event,
that funtion must also be called on the subsequent button release event
because otherwise wlroots thinks the button is kept pressed and it
causes issues with validating DnD requests from clients, where only one
button must be pressed. This was the case when a CSD client opens a
client-menu via `show_window_menu` request after pressing its window with
the right button because we were always not notifying button release
events while a menu is open.

So let's keep track of bound (pressed but not notified) buttons and notify
button release events only when the button is not bound, like we are doing
for key-state.

include/labwc.h

@@ -44,6 +44,7 @@
 #include <wlr/types/wlr_input_method_v2.h>
 #include <wlr/types/wlr_tablet_v2.h>
 #include <wlr/util/log.h>
+#include "common/set.h"
 #include "config/keybind.h"
 #include "config/rcxml.h"
 #include "input/cursor.h"
@@ -145,6 +146,8 @@ struct seat {
 	 */
 	struct cursor_context pressed;
 
+	struct lab_set bound_buttons;
+
 	struct {
 		bool active;
 		struct {

src/input/cursor.c

@@ -857,16 +857,15 @@ cursor_motion_absolute(struct wl_listener *listener, void *data)
 		event->time_msec, dx, dy);
 }
 
-static bool
+static void
 handle_release_mousebinding(struct server *server,
 		struct cursor_context *ctx, uint32_t button)
 {
 	if (server->osd_state.cycle_view) {
-		return false;
+		return;
 	}
 
 	struct mousebind *mousebind;
-	bool consumed_by_frame_context = false;
 
 	uint32_t modifiers = wlr_keyboard_get_modifiers(
 			&server->seat.keyboard_group->keyboard);
@@ -883,28 +882,12 @@ handle_release_mousebinding(struct server *server,
 					break;
 				}
 				continue;
-			case MOUSE_ACTION_DRAG:
-				if (mousebind->pressed_in_context) {
-					/*
-					 * Swallow the release event as well as
-					 * the press one
-					 */
-					consumed_by_frame_context |=
-						mousebind->context == LAB_SSD_FRAME;
-					consumed_by_frame_context |=
-						mousebind->context == LAB_SSD_ALL;
-				}
-				continue;
 			default:
 				continue;
 			}
-			consumed_by_frame_context |= mousebind->context == LAB_SSD_FRAME;
-			consumed_by_frame_context |= mousebind->context == LAB_SSD_ALL;
 			actions_run(ctx->view, server, &mousebind->actions, ctx);
 		}
 	}
-
-	return consumed_by_frame_context;
 }
 
 static bool
@@ -969,10 +952,7 @@ handle_press_mousebinding(struct server *server, struct cursor_context *ctx,
 				 * counted as a DOUBLECLICK.
 				 */
 				if (!double_click) {
-					/*
-					 * Swallow the press event as well as
-					 * the release one
-					 */
+					/* Swallow the press event */
 					consumed_by_frame_context |=
 						mousebind->context == LAB_SSD_FRAME;
 					consumed_by_frame_context |=
@@ -1020,6 +1000,7 @@ cursor_process_button_press(struct seat *seat, uint32_t button, uint32_t time_ms
 		 * so subsequent release always closes menu or selects menu item.
 		 */
 		press_msec = 0;
+		lab_set_add(&seat->bound_buttons, button);
 		return false;
 	}
 
@@ -1060,6 +1041,7 @@ cursor_process_button_press(struct seat *seat, uint32_t button, uint32_t time_ms
 		 * Note: This does not work for XWayland clients
 		 */
 		wlr_seat_pointer_end_grab(seat->seat);
+		lab_set_add(&seat->bound_buttons, button);
 		return false;
 	}
 
@@ -1072,6 +1054,7 @@ cursor_process_button_press(struct seat *seat, uint32_t button, uint32_t time_ms
 		return true;
 	}
 
+	lab_set_add(&seat->bound_buttons, button);
 	return false;
 }
 
@@ -1083,6 +1066,9 @@ cursor_process_button_release(struct seat *seat, uint32_t button,
 	struct cursor_context ctx = get_cursor_context(server);
 	struct wlr_surface *pressed_surface = seat->pressed.surface;
 
+	/* Always notify button release event when it's not bound */
+	const bool notify = !lab_set_contains(&seat->bound_buttons, button);
+
 	seat_reset_pressed(seat);
 
 	if (server->input_mode == LAB_INPUT_STATE_MENU) {
@@ -1097,15 +1083,11 @@ cursor_process_button_release(struct seat *seat, uint32_t button,
 					/*cursor_has_moved*/ false, &sx, &sy);
 			}
 		}
-		return false;
+		return notify;
 	}
 
 	if (server->input_mode != LAB_INPUT_STATE_PASSTHROUGH) {
-		if (pressed_surface) {
-			/* Ensure CSD clients see the release event */
-			return true;
-		}
-		return false;
+		return notify;
 	}
 
 	if (pressed_surface && ctx.surface != pressed_surface) {
@@ -1113,19 +1095,12 @@ cursor_process_button_release(struct seat *seat, uint32_t button,
 		 * Button released but originally pressed over a different surface.
 		 * Just send the release event to the still focused surface.
 		 */
-		return true;
+		return notify;
 	}
 
-	/* Bindings to the Frame context swallow mouse events if activated */
-	bool consumed_by_frame_context =
-		handle_release_mousebinding(server, &ctx, button);
+	handle_release_mousebinding(server, &ctx, button);
 
-	if (!consumed_by_frame_context) {
-		/* Notify client with pointer focus of button release */
-		return true;
-	}
-
-	return false;
+	return notify;
 }
 
 bool
@@ -1141,6 +1116,8 @@ cursor_finish_button_release(struct seat *seat, uint32_t button)
 		}
 	}
 
+	lab_set_remove(&seat->bound_buttons, button);
+
 	if (server->input_mode == LAB_INPUT_STATE_MOVE
 			|| server->input_mode == LAB_INPUT_STATE_RESIZE) {
 		if (resize_outlines_enabled(server->grabbed_view)) {