This is a problem that I have run into with alot of my guibutton positions and other things when I rescale my window, the HUD doesn't stay in the same place, even when I use the same code from vanilla, IDK how to fix it, but help would be appreciated.

Here is my code: http://pastebin.com/wGufAy3J

This is the resolution that you get passed in the RenderGameOverlayEvent:

new ScaledResolution(mc, mc.displayWidth, mc.displayHeight)

Thus, you can't store the ScaledResolution - your GUI is created ONCE, but the ScaledResolution is a new instance every time.

 

Use the ScaledResolution given to you by the event.