xwayland: Add WM_STATE modal property

Adds a modal property to indicate whether the surface wants to be a
modal.

include/wlr/xwayland.h

@@ -138,6 +138,7 @@ struct wlr_xwayland_surface {
 	struct wl_event_source *ping_timer;
 
 	// _NET_WM_STATE
+	bool modal;
 	bool fullscreen;
 	bool maximized_vert, maximized_horz;
 

include/xwayland/xwm.h

@@ -40,6 +40,7 @@ enum atom_name {
 	_NET_WM_MOVERESIZE,
 	_NET_WM_NAME,
 	_NET_SUPPORTING_WM_CHECK,
+	_NET_WM_STATE_MODAL,
 	_NET_WM_STATE_FULLSCREEN,
 	_NET_WM_STATE_MAXIMIZED_VERT,
 	_NET_WM_STATE_MAXIMIZED_HORZ,

xwayland/xwm.c

@@ -39,6 +39,7 @@ const char *atom_map[ATOM_LAST] = {
 	"_NET_WM_MOVERESIZE",
 	"_NET_WM_NAME",
 	"_NET_SUPPORTING_WM_CHECK",
+	"_NET_WM_STATE_MODAL",
 	"_NET_WM_STATE_FULLSCREEN",
 	"_NET_WM_STATE_MAXIMIZED_VERT",
 	"_NET_WM_STATE_MAXIMIZED_HORZ",
@@ -268,6 +269,9 @@ static void xsurface_set_net_wm_state(struct wlr_xwayland_surface *xsurface) {
 	int i;
 
 	i = 0;
+	if (xsurface->modal) {
+		property[i++] = xwm->atoms[_NET_WM_STATE_MODAL];
+	}
 	if (xsurface->fullscreen) {
 		property[i++] = xwm->atoms[_NET_WM_STATE_FULLSCREEN];
 	}
@@ -575,7 +579,9 @@ static void read_surface_net_wm_state(struct wlr_xwm *xwm,
 	xsurface->fullscreen = 0;
 	xcb_atom_t *atom = xcb_get_property_value(reply);
 	for (uint32_t i = 0; i < reply->value_len; i++) {
-		if (atom[i] == xwm->atoms[_NET_WM_STATE_FULLSCREEN]) {
+		if (atom[i] == xwm->atoms[_NET_WM_STATE_MODAL]) {
+			xsurface->modal = true;
+		} else if (atom[i] == xwm->atoms[_NET_WM_STATE_FULLSCREEN]) {
 			xsurface->fullscreen = true;
 		} else if (atom[i] == xwm->atoms[_NET_WM_STATE_MAXIMIZED_VERT]) {
 			xsurface->maximized_vert = true;
@@ -1028,7 +1034,10 @@ static void xwm_handle_net_wm_state_message(struct wlr_xwm *xwm,
 	for (size_t i = 0; i < 2; ++i) {
 		uint32_t property = client_message->data.data32[1 + i];
 
-		if (property == xwm->atoms[_NET_WM_STATE_FULLSCREEN] &&
+		if (property == xwm->atoms[_NET_WM_STATE_MODAL] &&
+				update_state(action, &xsurface->modal)) {
+			xsurface_set_net_wm_state(xsurface);
+		} else if (property == xwm->atoms[_NET_WM_STATE_FULLSCREEN] &&
 				update_state(action, &xsurface->fullscreen)) {
 			xsurface_set_net_wm_state(xsurface);
 		} else if (property == xwm->atoms[_NET_WM_STATE_MAXIMIZED_VERT] &&
@@ -1630,6 +1639,7 @@ struct wlr_xwm *xwm_create(struct wlr_xwayland *wlr_xwayland) {
 		xwm->atoms[NET_WM_STATE],
 		xwm->atoms[_NET_ACTIVE_WINDOW],
 		xwm->atoms[_NET_WM_MOVERESIZE],
+		xwm->atoms[_NET_WM_STATE_MODAL],
 		xwm->atoms[_NET_WM_STATE_FULLSCREEN],
 		xwm->atoms[_NET_WM_STATE_MAXIMIZED_VERT],
 		xwm->atoms[_NET_WM_STATE_MAXIMIZED_HORZ],