Right now it's possible to have 2 windows in a column through quarter tiling. But when a user needs to have 3 windows in a vertical column the only way to do it is by manual resizing. I think adding more tiling options is something a window manager should strive for. Here's how I think it could work: - Use alt+shif+drag to "draw" a rectangle to select the windows you want - OR trigger some popup with a list of windows in the current screen to pick - After selecting the windows ask what kind of tiling arrangement you want - For instance if 3 windows are selected allow picking a 3 window column (or row) - This could be represented visually or by text descriptions - The windows get tiled This is a basic idea. Right now what I do is manually resize windows and make them remember the size and position. I know kwin tiling scripts exist, but I don't use them and I don't think they're tightly integrated into the workflow since they depend on keyboard shortcuts. The idea is to make it painless to discover and use.
Instead of alt+shift+drag, it could be alt+shift+click to select windows, put a border around them for feedback. This could be useful for many functions that depend on a list of windows not just tiling. Automatically removing any selected windows after x seconds to avoid cases where the user accidentally selects one and doesn't know they can click again to remove.
This is now possible using KWin's new "Custom Tiling" feature in Plasma 5.27!