Menu: Settings → Window Settings → Keep Aspect Ratio
If you click on this menu item to activate it a check 
is placed next to the Keep Aspect Ratio and when you deactivate it the check disappears.
The resolution of an old TV Screen is 4:3 and this option keeps this aspect ratio when dragging the window.
activated function
If you change the windowsize the aspect ratio of 4:3 is kept. When you hold the SHIFT - key you can freely scale the window.
function not activated
You can freely scale the window. If you hold the SHIFT - key the window is scaled in 4:3 aspect ratio.
Note
If you resized the C64 Screen and have an ugly aspect ratio where pixels are looking incorrect and you can't get it back to a good looking aspect ratio just rightclick on the C64 screen and choose Windowsize 1:1 with Texture within the context menu.
Emu64 Help V4.xx Navigation
V4.xx: Table of Content
Portal: old-archiv
help text for Emu64 up to version 4.32.
