Request a Gnoblin titlebar

Provide a server titlebar when an application requests Gnoblin to draw its frame:

gnoblin.window_rule {
    match = {type = "window"},
    frame = {mode = "auto", renderer = "native", extents = {36, 0, 0, 0}},
}

Field	Accepted values	Default	Effect
mode	"off", "auto", "prefer-server", "replace"	"off"	"auto" adds a Gnoblin frame when the app requests server-side decoration.
renderer	Registered renderer name or "native"	"native"	Selects the frame renderer.
extents	Four integers from 0 to 256	{32, 1, 1, 1}	Top, right, bottom, and left frame sizes in logical pixels.

Apps that draw their own titlebars keep them in "auto" mode. See window frames for other modes and negotiation.