Window rules

Adding a rule

A rule says which windows it matches and what to do with them:

oxwm.rule.add({ class = "firefox", tag = 2 })
oxwm.rule.add({ instance = "mpv", floating = true })

Rules are checked when a window opens.

Matching

Field	Matches against
`class`	The window class
`instance`	The window instance name
`title`	The window title

A match is a substring, and it is case sensitive. class = "fire" matches firefox, and class = "Firefox" does not.

If a rule has more than one of these fields, all of them have to match:

oxwm.rule.add({ class = "firefox", title = "Library", floating = true })

That floats the Firefox downloads window and leaves the main window tiled.

Finding the class

Run xprop and click the window:

xprop | grep WM_CLASS

WM_CLASS(STRING) = "Navigator", "firefox"

The first value is the instance and the second is the class. For the title, look at WM_NAME.

What a rule can set

Field	Type	Effect
`floating`	boolean	Open the window floating
`fullscreen`	boolean	Open the window fullscreen
`tag`	integer	Send the window to this tag
`monitor`	integer	Send the window to this monitor
`focus`	boolean	Switch to the window’s tag when it opens
`width`	number	Starting width in the scrolling layout

tag counts from 1, so tag = 2 is the second tag. monitor counts from 0, so monitor = 0 is the first monitor.

Examples

Send a chat client to tag 9 and follow it there:

oxwm.rule.add({ class = "discord", tag = 9, focus = true })

Float a few utilities:

oxwm.rule.add({ instance = "gimp", floating = true })
oxwm.rule.add({ class = "Pavucontrol", floating = true })
oxwm.rule.add({ title = "Picture-in-Picture", floating = true })

Put a game fullscreen on the second monitor:

oxwm.rule.add({ class = "steam_app", fullscreen = true, monitor = 1 })

More than one match

Every rule that matches a window is applied, in the order you added them. If two matching rules set a tag, the window gets both tags. For floating, the last matching rule decides, so put the general rules first and the specific ones after.