Don't send motion if the cursor hasn't moved

Prevents GTK+ comboboxes from immediately closing.

include/sway/input/seat.h

@@ -70,6 +70,7 @@ struct sway_seat {
 	double op_ref_lx, op_ref_ly;         // cursor's x/y at start of op
 	double op_ref_width, op_ref_height;  // container's size at start of op
 	double op_ref_con_lx, op_ref_con_ly; // container's x/y at start of op
+	bool op_moved;                       // if the mouse moved during a down op
 
 	uint32_t last_button;
 	uint32_t last_button_serial;

sway/input/cursor.c

@@ -225,6 +225,7 @@ static void handle_down_motion(struct sway_seat *seat,
 		double sy = seat->op_ref_con_ly + moved_y;
 		wlr_seat_pointer_notify_motion(seat->wlr_seat, time_msec, sx, sy);
 	}
+	seat->op_moved = true;
 }
 
 static void handle_move_motion(struct sway_seat *seat,

sway/input/seat.c

@@ -963,6 +963,7 @@ void seat_begin_down(struct sway_seat *seat, struct sway_container *con,
 	seat->op_ref_ly = seat->cursor->cursor->y;
 	seat->op_ref_con_lx = sx;
 	seat->op_ref_con_ly = sy;
+	seat->op_moved = false;
 }
 
 void seat_begin_move(struct sway_seat *seat, struct sway_container *con,
@@ -1034,7 +1035,9 @@ void seat_end_mouse_operation(struct sway_seat *seat) {
 		// during the operation.
 		seat->cursor->previous.x = seat->op_ref_lx;
 		seat->cursor->previous.y = seat->op_ref_ly;
+		if (seat->op_moved) {
 			cursor_send_pointer_motion(seat->cursor, 0, true);
+		}
 	} else {
 		cursor_set_image(seat->cursor, "left_ptr", NULL);
 	}