Fill Right Not Working As Expected?

Hi! I'm curious to know if I'm misinterpreting the fill right setting in the Custom Move/Resize Window action.

This is the setting and scenario in a screenshot. Based on the way it's worded, I would expect this action to fill the entirety of the empty space to the left of the browser window. Instead, it doesn't seem to do anything.

(FYI I have Ctrl+Opt+RightArrow as snap to right half of screen. I'm trying to get it so that another press of the same hotkey will fill whatever space is remaining)

this stuff is always relative to the screen, it can't fill to other windows. I know that this would be quite useful but unfortunately the available APIs make this pretty hard to achieve.

I'm not sure I understand what the action does when you say "relative to the screen" - could you explain it in more detail?

Let me take a stab - are you saying that if the window on the right (in my screenshot) had it's left edge against the other window, "fill right" would extend it to the right edge of the screen? But since the window is starting out with it's right edge already against the right edge of the screen, there's nothing more to fill?

correct, it would just fill up the remaining space to the edge of the screen ;-(