fix: clamp tiling windows with their working rects

[mzhu-zx]

If a window is on the edge of the monitor and has a large shadow border, the computed rectangle can exceed it ancestor monitor's the working rectangle, which places it on a neighbor monitor instead. The DWM will render the window either too long or too wide in a dual monitor setting where two monitors of different sizes are not perfectly aligned.

To fix this, a new function clamp_strictly is added to restrict all computed rectangles in tiling mode to the working rectangle of the ancestor monitor. The existing clamp function cannot guarantee this. Consider rectangles in (x, y, w, h): (0, 0, 3, 3) and (1, 1, 3, 3) where the latter is the outer. The intersection of those 2 rectangles needs to have width and height 2 instead of 3.

[lars-berger]

@mzhu-zx Thank you for the PR! 🙌

I just tried your fix branch - it's clamping successfully to the bounds of the monitor. Added a fix just now so that it only affects tiling windows (e.g. to allow floating windows in between the edges of two monitors).

However, I'm having trouble finding an example window to test this out with. Would you mind showing a screenshot of a window with excessive window borders before/after the fix?

A problem I'm noticing with the fix is that it causes the windows to not take up the proper width/height with 0px outer gaps:

Also, not sure if this affects your use case but there's an adjust-borders command available for tweaking window-specific borders.