xwayland: stop translating _NET_WM_STRUT_PARTIAL coordinates

Translating the right/bottom coordinates from offsets to absolute
coordinates in wlroots (rather than in the compositor) was supposed to
be more reliable, since wlroots had access to the X11 screen size.

It ended up being less reliable, because the screen size values
(xwm->screen->width_in_pixels/height_in_pixels) are not updated when the
output layout changes.

So let's remove the translation from wlroots, and let the compositor
figure it out. From what I can understand of the current XWayland code,
the X11 screen size should generally match the overall wlr_output_layout
bounding box, which the compositor has access to.

include/wlr/xwayland/xwayland.h

@@ -124,8 +124,11 @@ struct wlr_xwayland_surface {
 	xcb_icccm_wm_hints_t *hints;
 	xcb_size_hints_t *size_hints;
 	/*
-	 * _NET_WM_STRUT_PARTIAL (used by e.g. XWayland panels;
+	 * _NET_WM_STRUT_PARTIAL (used by e.g. XWayland panels).
-	 * right/bottom are translated into root x/y coordinates)
+	 * Note that right/bottom values are offsets from the lower
+	 * right corner of the X11 screen, and the exact relation
+	 * between X11 screen coordinates and the wlr_output_layout
+	 * depends on the XWayland implementation.
 	 */
 	xcb_ewmh_wm_strut_partial_t *strut_partial;
 

xwayland/xwm.c

@@ -775,20 +775,6 @@ static void read_surface_strut_partial(struct wlr_xwm *xwm,
 		return;
 	}
 	xcb_ewmh_get_wm_strut_partial_from_reply(xsurface->strut_partial, reply);
-
-	/*
-	 * Translate right/bottom into root x/y coordinates here since
-	 * the compositor is ignorant of X11 screen width/height.
-	 *
-	 * (This could result in an incorrect position if the X11 screen
-	 * size changes but _NET_WM_STRUT_PARTIAL doesn't. It's probably
-	 * not worth the additional code to fix this corner case.)
-	 */
-	xsurface->strut_partial->right =
-		xwm->screen->width_in_pixels - xsurface->strut_partial->right;
-	xsurface->strut_partial->bottom =
-		xwm->screen->height_in_pixels - xsurface->strut_partial->bottom;
-
 	wl_signal_emit_mutable(&xsurface->events.set_strut_partial, NULL);
 }