Various UI Tweaks

[NullSenseStudio]

• When there are multiple image editors, generating from an open image source or upscaling will now pick the image from the image editor it was executed from.
• Image editors with image pin activated will no longer be replaced with generated images.
• Cancel generator operator has been slightly changed to better differentiate it from release generator.
• Image texture nodes will now fill the shader editor view better instead of just the bottom right corner.