Hello xmonad world. X.L.LayoutBuilderP is a layout combinator similar to X.L.LayoutBuilder (and is based on it). But LayoutBuilder places fixed number of windows into each rectangle. LayoutBuilderP places windows matching given Property (or any other predicate) into one rectangle. darcs could not record my patch because of warnings in X.A.DynamicWorkspaces: XMonad/Actions/DynamicWorkspaces.hs:40:0: Warning: The import of `XMonad.Actions.CopyWindow' is redundant except perhaps to import instances from `XMonad.Actions.CopyWindow' To import instances alone, use: import XMonad.Actions.CopyWindow() XMonad/Actions/DynamicWorkspaces.hs:41:0: Warning: The import of `XMonad.Prompt' is redundant except perhaps to import instances from `XMonad.Prompt' To import instances alone, use: import XMonad.Prompt() <no location info>: Failing due to -Werror. Test failed! So, I removed redudant imports from that module (see the second patch). WBR, Ilya Portnov.