Don't send button events to surfaces when dragging or resizing

It turns out sending button events during all seat operations is not
desirable. This patch introduces a new property
`seatop_impl.allows_events` which allows each operation to define
whether button events should be passed to the surface or not.

The `down` seat operation is the only one that supports this. As all the
other seatops don't support it, the calls to seat_pointer_notify_button
prior to starting them have been removed.

include/sway/input/seat.h

@@ -15,6 +15,7 @@ struct sway_seatop_impl {
 	void (*unref)(struct sway_seat *seat, struct sway_container *con);
 	void (*render)(struct sway_seat *seat, struct sway_output *output,
 			pixman_region32_t *damage);
+	bool allows_events;
 };
 
 struct sway_seat_device {
@@ -239,4 +240,6 @@ void seatop_unref(struct sway_seat *seat, struct sway_container *con);
 void seatop_render(struct sway_seat *seat, struct sway_output *output,
 		pixman_region32_t *damage);
 
+bool seatop_allows_events(struct sway_seat *seat);
+
 #endif

sway/input/cursor.c

@@ -613,7 +613,9 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
 		} else {
 			state_erase_button(cursor, button);
 		}
+		if (seatop_allows_events(seat)) {
 			seat_pointer_notify_button(seat, time_msec, button, state);
+		}
 		return;
 	}
 
@@ -682,7 +684,6 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
 	if (cont && resize_edge && button == BTN_LEFT &&
 			state == WLR_BUTTON_PRESSED && !is_floating) {
 		seat_set_focus_container(seat, cont);
-		seat_pointer_notify_button(seat, time_msec, button, state);
 		seatop_begin_resize_tiling(seat, cont, button, edge);
 		return;
 	}
@@ -713,7 +714,6 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
 			}
 			cursor_set_image(seat->cursor, image, NULL);
 			seat_set_focus_container(seat, cont);
-			seat_pointer_notify_button(seat, time_msec, button, state);
 			seatop_begin_resize_tiling(seat, cont, button, edge);
 			return;
 		}
@@ -729,7 +729,6 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
 				cont = cont->parent;
 			}
 			seat_set_focus_container(seat, cont);
-			seat_pointer_notify_button(seat, time_msec, button, state);
 			seatop_begin_move_floating(seat, cont, button);
 			return;
 		}
@@ -740,7 +739,6 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
 			state == WLR_BUTTON_PRESSED) {
 		// Via border
 		if (button == BTN_LEFT && resize_edge != WLR_EDGE_NONE) {
-			seat_pointer_notify_button(seat, time_msec, button, state);
 			seatop_begin_resize_floating(seat, cont, button, resize_edge);
 			return;
 		}
@@ -758,7 +756,6 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
 				WLR_EDGE_RIGHT : WLR_EDGE_LEFT;
 			edge |= cursor->cursor->y > floater->y + floater->height / 2 ?
 				WLR_EDGE_BOTTOM : WLR_EDGE_TOP;
-			seat_pointer_notify_button(seat, time_msec, button, state);
 			seatop_begin_resize_floating(seat, floater, button, edge);
 			return;
 		}
@@ -775,8 +772,6 @@ void dispatch_cursor_button(struct sway_cursor *cursor,
 			seat_set_focus(seat, node);
 		}
 
-		seat_pointer_notify_button(seat, time_msec, button, state);
-
 		// If moving a container by it's title bar, use a threshold for the drag
 		if (!mod_pressed && config->tiling_drag_threshold > 0) {
 			seatop_begin_move_tiling_threshold(seat, cont, button);

sway/input/seat.c

@@ -1234,3 +1234,7 @@ void seatop_render(struct sway_seat *seat, struct sway_output *output,
 		seat->seatop_impl->render(seat, output, damage);
 	}
 }
+
+bool seatop_allows_events(struct sway_seat *seat) {
+	return seat->seatop_impl && seat->seatop_impl->allows_events;
+}

sway/input/seatop_down.c

@@ -58,6 +58,7 @@ static const struct sway_seatop_impl seatop_impl = {
 	.finish = handle_finish,
 	.abort = handle_abort,
 	.unref = handle_unref,
+	.allows_events = true,
 };
 
 void seatop_begin_down(struct sway_seat *seat, struct sway_container *con,