Screen buffer size in post draw

[Azenris]

When I move the window from one screen to the other, the internal screen buffer size seems to be wrong.

I have a window that calculate the resolution and it seems to give me the correct variables I desire.
On my
primary monitor (1920x1200) i get the resolution 240x150 ( perfect divsion of 8 )
If i go fullscreen it works perfectly.

Now, if I drag this window to my left monitor
secondary monitor (1920x1080) i get the resolution 320x180 perfect divsion of 6 )
If i go fullscreen, it has problems.

What problem?
I get a weird bit at the bottom of the screen. This part is 120 pixels high. ( 1200 - 1080 )

What do I think it is?
To me it feels like the screenbuffer is updating to the window size of the primary monitor.

Questions
1) Are there any function to get the screen buffer width & height so I can confirm for myself.
2) Should the internal screen buffer size be updating?
3) Am i thinking about this wrong?
4) What do I need to do

For some testing I added some drawing at the end of my post draw

draw_sprite( spr_colour_picker_marker, 0, 0, 0 );
draw_sprite( spr_colour_picker_marker, 0, window_get_width(), 0 );
draw_sprite( spr_colour_picker_marker, 0, 0, window_get_height() );
draw_sprite( spr_colour_picker_marker, 0, window_get_width()/2, window_get_height() );
draw_sprite( spr_colour_picker_marker, 0, window_get_width(), window_get_height() );

// forced locations
draw_sprite( spr_colour_picker_marker, 0, 960, 1200 );
draw_sprite( spr_colour_picker_marker, 0, 960, 1200 );

This looks to me like the screen buffer is 1200h forced onto a window thats 1080h.
You can see the draws of draw_sprite( spr_colour_picker_marker, 0, 960, 1200 );
at the bottom of the screen.


If you need any more information let me know. Its kinda all confusing me, and I keep trying different things, randomly at this point.
Which is why i wonder for checking the screenbuffer height and stuff.

Anyway ty.



I know its me doing something wrong, just framing it from my thought process