drag and drop (dnd) through resize zone

[Arnaudv6]

In v0.7.2, when dragging from one view to another,
(with source view having shadows and overlapping on destination view)
user can't drop through (overlapping) source view's shadow to destination view.

[Consolatis]

Is this for client side decorations or server side ones?

Server side shadows should not exist in terms of hitbox detection, e.g. dropping something there should land on whatever is behind those shadows.

[Arnaudv6]

Both CSD ((gthumb) and SSD (thunar).
Maybe source windows's shadow are not hitboxes, but they're "opaque": window bellow don't receive drops through them.
screenshot_2024-05-19-18:45:04.webm

[johanmalm]

Feels like there are two options:

1. Decide that DND doesn't work through drop-shadows
2. Overload get_cursor_context() to optionally ignore SSD drop-shadows. It's possible this could be done for CSD, but is likely to be hacky.

I prefer (1).

The disadvantage of (2) it may result in different behaviors depending on SSD/CSD, and it add complexity to an already complex code-path (get_cursor_context())

Ref:

• https://github.com/labwc/labwc/blob/master/src/desktop.c#L271

• labwc/src/dnd.c

  Line 68 in 89589f1

  struct cursor_context ctx = get_cursor_context(seat->server);

[Consolatis]

SSD shadows should really not get detected:

labwc/src/ssd/ssd_shadow.c

Line 220 in 89589f1

scene_buf->point_accepts_input = never_accepts_input;

-> https://gitlab.freedesktop.org/wlroots/wlroots/-/blob/0.17/types/scene/wlr_scene.c?ref_type=heads#L1059-1106

Maybe this is actually about the invisible resize area?
@Arnaudv6 does the same happen with server side decorations when you disable shadows?

[Arnaudv6]

@Consolatis yes it does, good catch, sorry my bug was unspecific

[Consolatis]

Hm.. we need to detect the invisible resize area to well, resize the window.

Maybe we can either disable it or also set point_accepts_input temporarily when in dnd mode. As far as I remember we do have a function that disables the dnd icon surface during hitbox detection already so we could likely hook into there.