Panel state inconsistent at left and top edge of screen

[mook765]

When I set the panel to "always hide" or "hide intelligently" the following happens:

When I place a horizontal panel at the top of the screen and move the pointer to the most top of the screen, the panel loses focus.

When I place the panel as desk-bar or vertical at the left edge of the screen and move the pointer to the most left of the screen, the panel loses focus.

I tried to play around with the opacity settings and one can see the panel flickering while moving the pointer along the screen-edge if the opacity is set to 100 for "enter" and 0 for "leave"

The effect is that the panel refuse to appear when I move the pointer to fast to the screen-edge and I have to hit the few pixel wide stripe exactly which one can see when the panel is hidden.

When I place the panel at the lower or right edge of the screen the panel does not lose focus when I move the pointer to the corresponding screen-edge, it works just beautiful.

This happens with a fresh install of Ubuntu Studio 18.10.
It doesn't appear to be hardware-related as the panel works nicely in Ubuntu Studio 16.04 or 18.04 which I still have installed (Triple-Boot).

The installed version of xfce4-panel is 4.12.2-1ubuntu1

[mook765 (mook765)]

Correction: The installed version of xfce4-panel is 4.13.3-1ubuntu1
I forgot that I was running 18.04 while typing the report, sorry for that

[Theo Linkspfeifer (lastonestanding)]

Bug 1715037 and bug 1795135 are somewhat related.

Which GTK3 theme does Ubuntu Studio use?

[mook765 (mook765)]

In Ubuntu Studio 18.10 NumixBlue is the default-theme.
Currently I use Arc-dark from official reopsitories.
It doesn't seem to matter which theme I use, I can reproduce the same behaviour with all pre-installed themes.

[mook765 (mook765)]

[Bug 1715037](https://bugs.launchpad.net/bugs/1715037) seems to be related.
At the moment, a horizontal panel at the lower edge is the only reliable
postition for me.
When I move the pointer to the left or right end of the panel though, the panel
loses focus, but that's not too bad.

[Theo Linkspfeifer (lastonestanding)]

I suggest testing with the environmental variable "GDK_CORE_DEVICE_EVENTS=1" which is mentioned in the second bug report.

[mook765 (mook765)]

Perfect, adding 'export GDK_CORE_DEVICE_EVENTS=1' to ~/.profile and logging in again solved the problem.
Thank you so much for looking into this.