Ninths, Eighths, Corner Thirds and Halving: The Sizes With No Interface

How to bind a command with no interface

Every hidden command is bound the same way: write a dictionary containing a keycode and a modifier value into the preference domain, then restart the app.

defaults write com.knollsoft.Rectangle COMMAND_NAME -dict-add keyCode -float KEY modifierFlags -float MODS
killall Rectangle && open -a Rectangle

Modifier values are summed:

Keycodes for the number and letter rows are in the keycodes reference. The values used repeatedly below: <code>18</code> is the 1 key, <code>19</code> is 2, <code>20</code> is 3, <code>8</code> is C, <code>30</code> is ], <code>33</code> is [, and <code>123</code>–<code>126</code> are the arrow keys.

Ninths: a 3×3 grid

Nine commands dividing the screen into a three-by-three grid. On a 32-inch or ultrawide display this is a genuinely usable density; on a laptop it is not.

# keys: topLeftNinth topCenterNinth topRightNinth
#       middleLeftNinth middleCenterNinth middleRightNinth
#       bottomLeftNinth bottomCenterNinth bottomRightNinth

# ctrl+opt+shift+1 .. 3 for the top row
defaults write com.knollsoft.Rectangle topLeftNinth -dict-add keyCode -float 18 modifierFlags -float 917504
defaults write com.knollsoft.Rectangle topCenterNinth -dict-add keyCode -float 19 modifierFlags -float 917504
defaults write com.knollsoft.Rectangle topRightNinth -dict-add keyCode -float 20 modifierFlags -float 917504

The natural binding scheme maps the number row's three rows of three to the grid's geometry — 1/2/3 with one modifier set for the top row, another for the middle, another for the bottom. Nine bindings is a lot to memorise, so most people who use ninths bind only the ones they actually need, typically the centre and the corners.

Eighths: a 4×2 grid

Four columns by two rows. This suits ultrawide displays much better than ninths, because it divides the horizontal axis — which is where an ultrawide has space — without over-dividing the vertical, where it does not.

# keys: topLeftEighth topCenterLeftEighth topCenterRightEighth topRightEighth
#       bottomLeftEighth bottomCenterLeftEighth bottomCenterRightEighth bottomRightEighth

defaults write com.knollsoft.Rectangle topLeftEighth -dict-add keyCode -float 18 modifierFlags -float 917504
defaults write com.knollsoft.Rectangle bottomLeftEighth -dict-add keyCode -float 18 modifierFlags -float 1966080

Corner two-thirds

Four commands producing a two-thirds region anchored to a corner — a large primary area with an L-shaped remainder. This is the layout for a dominant main window plus two smaller companions, and it is not otherwise reachable.

# keys: topLeftThird topRightThird bottomLeftThird bottomRightThird
# (these are two-thirds regions, and they cycle through variants when repeated)

defaults write com.knollsoft.Rectangle topLeftThird -dict-add keyCode -float 18 modifierFlags -float 917504

They cycle through several calculations when pressed repeatedly, so one binding reaches more than one geometry. Worth experimenting with before deciding how many you need.

Doubling and halving

Eight commands that double or halve a window's width or height, growing or shrinking toward a named direction. The direction in the name is where the *centre* of the window moves as a result of the resize — which is worth reading twice, because it is the opposite of what most people assume the first time.

# ctrl+option+shift+right → double width rightward
defaults write com.knollsoft.Rectangle doubleWidthRight -dict-add keyCode -float 124 modifierFlags -float 917504

# ctrl+option+shift+left → halve width, keeping the left edge
defaults write com.knollsoft.Rectangle halveWidthLeft -dict-add keyCode -float 123 modifierFlags -float 917504

Binary sizing is a different mental model from fractions and suits people who think in terms of "twice as wide" rather than "two thirds of the screen". Four bindings — double and halve, width and height — cover most of the value.

Custom exact sizes

Two commands worth knowing about individually. The first centres a window at an exact pixel size, which is the correct tool for anyone who needs a repeatable viewport — testing a layout at a specific width, recording a screencast at a fixed dimension, or matching a design canvas:

defaults write com.knollsoft.Rectangle specified -dict-add keyCode -float 8 modifierFlags -float 1966080
defaults write com.knollsoft.Rectangle specifiedWidth -float 1680
defaults write com.knollsoft.Rectangle specifiedHeight -float 1050

The second centres horizontally but sits the window slightly above the vertical centre, which reads as better balanced to the eye — the same principle as optical centring in typography:

defaults write com.knollsoft.Rectangle centerProminently -dict-add keyCode -float 8 modifierFlags -float 1835305

Both are considerably more useful than their obscurity suggests. The exact-size command in particular replaces a whole category of fiddly manual resizing for anyone doing repeatable visual work.

Questions