Brush vs. UI behavior curiosity

Software ART
1

This is just a cosmetic thing that has no impact on the image, but I’m curious. Note the visual differences in interaction between the brush and the left / right panels:

Left

over
over572×395 36.7 KB

Right

under
under536×296 34.6 KB

When the button is released there’s no lingering “paint” on the UI in either case, but it does look a bit “wrong” to even temporarily overwrite (overpaint?) anything outside the photo when editing. Even on the right side, a bit of the image border is overwritten.

Something in the relative Z order? Or is this something unique to the Windows version?

2

1.25.10 version, Linux:

Right

1
11279×651 74.4 KB

Up:

2
2980×845 66.5 KB

It behaves exactly the same to the left and down.

3

Checked all 4 sides running latest ART built from sources on Gnome with Wayland - no brush painting outside of the image.

4

Looks like there are various Z-order relationships out there. Off the image but under the UI, off the image and on top of (some of) the UI, etc.

It’s purely cosmetic and it may be library related rather that specific to ART. GTK / Cairo?