xwayland selection: further cleanup on Xwayland exit

This is necessary if our last primary/clipboard selection was on Xwayland,
and we try to paste to native wayland after Xwayland died

include/wlr/xwm.h

@@ -108,6 +108,7 @@ void xwm_set_cursor(struct wlr_xwm *xwm, const uint8_t *pixels, uint32_t stride,
 int xwm_handle_selection_event(struct wlr_xwm *xwm, xcb_generic_event_t *event);
 
 void xwm_selection_init(struct wlr_xwm *xwm);
+void xwm_selection_finish(struct wlr_xwm *xwm);
 
 void xwm_set_seat(struct wlr_xwm *xwm, struct wlr_seat *seat);
 

xwayland/selection.c

@@ -826,6 +826,30 @@ void xwm_selection_init(struct wlr_xwm *xwm) {
 	selection_init(xwm, &xwm->primary_selection, xwm->atoms[PRIMARY]);
 }
 
+void xwm_selection_finish(struct wlr_xwm *xwm) {
+	if (!xwm) {
+		return;
+	}
+	if (xwm->selection_window) {
+		xcb_destroy_window(xwm->xcb_conn, xwm->selection_window);
+	}
+	if (xwm->seat) {
+		if (xwm->seat->selection_source &&
+				xwm->seat->selection_source->cancel == data_source_cancel) {
+			wlr_seat_set_selection(xwm->seat, NULL,
+					wl_display_next_serial(xwm->xwayland->wl_display));
+		}
+		if (xwm->seat->primary_selection_source &&
+				xwm->seat->primary_selection_source->cancel == primary_selection_source_cancel) {
+			wlr_seat_set_primary_selection(xwm->seat, NULL,
+					wl_display_next_serial(xwm->xwayland->wl_display));
+		}
+		wl_list_remove(&xwm->seat_selection.link);
+		wl_list_remove(&xwm->seat_primary_selection.link);
+	}
+
+}
+
 static void xwm_selection_set_owner(struct wlr_xwm_selection *selection,
 		bool set) {
 	if (set) {

xwayland/xwm.c

@@ -1092,9 +1092,7 @@ void xwm_destroy(struct wlr_xwm *xwm) {
 	if (!xwm) {
 		return;
 	}
-	if (xwm->selection_window) {
-		xcb_destroy_window(xwm->xcb_conn, xwm->selection_window);
-	}
+	xwm_selection_finish(xwm);
 	if (xwm->cursor) {
 		xcb_free_cursor(xwm->xcb_conn, xwm->cursor);
 	}
@@ -1114,10 +1112,6 @@ void xwm_destroy(struct wlr_xwm *xwm) {
 	wl_list_for_each_safe(xsurface, tmp, &xwm->unpaired_surfaces, link) {
 		wlr_xwayland_surface_destroy(xsurface);
 	}
-	if (xwm->seat) {
-		wl_list_remove(&xwm->seat_selection.link);
-		wl_list_remove(&xwm->seat_primary_selection.link);
-	}
 	wl_list_remove(&xwm->compositor_surface_create.link);
 	xcb_disconnect(xwm->xcb_conn);