Python Gui has white border - help?

[pomtom44]

Hi all.
Not sure if this is the best place to post - i have posted in a few places.
I have a simple python GUI which loads on boot on my raspberry pi tinycore install.
It uses tkinter and has what i believe is all the fullscreen settings,
however it has a thin white line at the top and left size
I have tried moving the python window and resizing to be slightly larger than the screen
as well as tried setting the color to black
or using hdmi overscan to hide it off the edge, but im not sure what else to try.

not sure what info is needed to help so let me know if you need anything else.

thanks in advance

[gadget42]

perhaps the monitor has "auto" adjustment to eliminate any misalignment?

[pomtom44]

perhaps the monitor has "auto" adjustment to eliminate any misalignment?

I didn't consider that
Although it is a cheap unbranded odd resolution display, so not sure if it would have that feature?
Also it only shows when the python script runs, so im 95% sure its something to do with the "full screen" loading on the tkinter gui
I had to mess around for a while to get the maximise / minimise buttons to be hidden properly so it could still be a "border" on that window