Grid-based Tiling Window Management

Many years ago, a coworker of mine showed me Window's "quick tiling" feature, where you would press Window-LeftArrow or Window-RightArrow to snap the current window to the left or right half of the screen. I then found that KDE on Linux had that same feature and the ability to snap to the upper-left, lower-left, upper-right, or lower-right quarter of the screen. I assigned those actions to the Meta-Home, Meta-End, Meta-PgUp, and Meta-PgDn shortcuts. (I'm going to use "Meta" as a generic term to mean the modifier key that on Windows machines has a Windows logo, on Linux machines has a Ubuntu or Tux logo, and Macs call "command".) Being able to arrange windows on screen quickly and neatly with keyboard shortcuts worked extremely well and quickly became a capability central to how I work.

Then I bought a 4K monitor.

With a 4K monitor, I could still arrange windows in the same way, but now I had 4 times the number of pixels. There was room on the screen to have a lot more windows that I could see at the same time and remain readable. I wanted a 4x4 grid on the screen, with the ability to move windows around on that grid, but also to resize windows to use multiple cells within that grid.

Further complicating matters is the fact that I use that 4K monitor along with the laptop's !FullHD screen which is 1920x1080. Dividing that screen into a 4x4 grid would be awkward; I wanted to retain a 2x2 grid for that screen, and keep a consistent mechanism for moving windows around on that screen and across screens.

KDE (Linux)

Unfortunately, KDE does not have features to support such a setup. So I went looking for a programatic way to control window size and placement on KDE/X11. I found three commandline tools that among them offered primitives I could build upon: xdotool, wmctrl, and xprop.

My solution was to write a Python program which took two arguments: a command and a direction.

The commands were 'move', 'grow', and 'shrink', and the directions 'left', 'right', 'up', and 'down'. And one additional command 'snap' with the location 'here' to snap the window to the nearest matching grid cells. The program would identify the currently active window, determine which grid cell was a best match for the action, and execute the appropriate xdotool commands. Then I associated keyboard shortcuts with those commands. Meta-Arrow keys for moving, Meta-Ctrl-Arrow keys to grow the window by a cell in the given direction, Meta-Shift-Arrow to shrink the window by a cell from the given direction, and Meta-Enter to snap to the closest cell.


Conceptually, that's not all that complicated to implement, but in practice:

Window geometry has to be adjusted for window decorations. But there appears to be a bug with setting the position of a window. The window coordinates used by the underlying tools for setting and getting the geometries do not include the frame, except for setting the position of the window, on windows that have a 'client' of the machine name instead of N/A. Getting the position, getting the size, and setting the size, all use the non-frame values. Windows with a client of N/A use the non-frame values for everything. A border width by title bar height offset error for only some of the windows proved to be a vexing bug to track down.

The space on a secondary monitor where the taskbar would be is also special, even if there is no task bar on that monitor; attempting to move a window into that space causes the window to shift up out of that space, so there remains an unused border on the bottom of the screen. Annoying, but I have found no alternative.

Move operations are not instantaneous, so setting a location and immediately querying it will yield the old coordinates for a short period.

A window which is maximized does not respond to the resize and move commands (and attempting it will cause xdotool to hang for 15 seconds), so that has to be detected and unmaximized.

A window which has been "Quick Tiled" using KDE's native quick-tiling feature acts like a maximized window, but does not set the maximized vert or maximized horz state flags, so cannot be detected with xprop, and to get it out of the KDE quick tiled state, it must be maximized and then unmaximized. So attempting to move a KDE quick tiled window leads to a 15 second pause, then the window maximizing briefly, and then resizing to the desired size. In practice, this is not much of an issue since my tool has completely replaced my use of KDE's quick-tiling.


I recently whined to a friend about not having the same window management setup on OS X; and he pointed me in the direction of a rather intriguing open source tool called Hammerspoon which lets you write Lua code to automate tasks in OS X and can assign keyboard shortcuts to those actions. That has a grid module that offers the necessary primitives to accomplish the same goal.

After installing Hammerspoon, launching it, and enabling Accessibility for Hammerspoon (so that the OS will let it control application windows), use init.lua as your ~/.hammerspoon/init.lua and reload the Hammerspoon config. This will set up the same set of keyboard shortcuts for moving application windows around as described in the KDE (Linux) section. For those who use OS X as their primary system, that set of shortcuts are going to conflict with (and therefore override) many of the standard keyboard shortcuts. Changing the keyboard shortcuts to add the Option key as part of the set of modifiers for all of the shortcuts should avoid those collisions at the cost of either needing another finger in the chord or putting a finger between the Option and Command keys to hit them together with one finger.

I was pleasantly surprised with how easily I could implement this approach using Hammerspoon.


Simple demo of running this on KDE:

(And that beautiful background is a high resolution photo by a friend and colleague, Sai Rupanagudi.)



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