X11 Session used with fractional scale: Too small proportion of top panel

[Letterus]

What Happened?

Only was using Wayland session, but now logged in into X11 session. Besides some smaller aspects (windows do not have the same size as on Wayland) I've got the issue that a full screen window is partly hidden behind the top panel. Looks like measuring its size is still broken on X11 (I think it was on Wayland as well, but there it was too big, not too small).

Steps to Reproduce

1. Enable fractional scaling, set it to 1.25x.
2. Log in to X11 session.
3. See above

Expected Behavior

Window proportion should be the same as when using Wayland (in case that's possible).

OS Version

8.x (Early Access)

Session Type

Classic Session (X11, This is the default)

Software Version

Latest release (I have run all updates)

Log Output

No response

Hardware Info

Thinkpad X280, i915 graphics

[Letterus]

Same is true for dock: It appears to early when moving the mouse pointer down. So it appears before the pointer actual reaches its the bottom of the screen or even the area of the size of the dock graphics.

[wout]

Same problem here:

It seems like the height of the top panel is calculated at 1x height. I'm using 3000x2000@2x under X.