windows briefly appear before size/position rules (e.g., ResizeTo, SnapToEdge) take effect about labwc

[Consolatis]

The window rules are set up to have different events even though only ON_FIRST_MAP is implemented so far (and is the default if the event argument is missing from the window rule). I guess we could just add another event like ON_CREATE or something like that. However, I am also not sure about the implications of having the event run before map.

E.g. something like this:

<windowRule identifier="foot" event="onCreate">
    <action name="SnapToEdge" direction="up" />
</windowRule>

[tokyo4j]

This can be solved by applying window rules before the client maps a surface. I confirmed the following patch solves the flickering issue for xdg-shell clients, but I'm not sure if it's okay to apply normal actions against views that have not been mapped.

diff --git a/src/xdg.c b/src/xdg.c
index 4e6d6dad..ce06259a 100644
--- a/src/xdg.c
+++ b/src/xdg.c
@@ -795,6 +795,8 @@ xdg_surface_new(struct wl_listener *listener, void *data)
 	CONNECT_SIGNAL(xdg_surface, xdg_toplevel_view, new_popup);
 
 	wl_list_insert(&server->views, &view->link);
+
+	window_rules_apply(view, LAB_WINDOW_RULE_EVENT_ON_FIRST_MAP);
 }
 
 void

Another approach would be disabling the view node until the client applies the geometry requested by window rules, but the problem is wlroots automatically sends wl_surface.leave and doesn't return frame callback if the node is disabled, thus the configure event timeouts.

[tokyo4j]

I think onCreate is usefu also when the user want to open a fullscreen window in a fixed output (#1859).