X.U.NamedScratchpad: Initialise if necessary

[slotThe]

Description

Fixes: https://github.com/xmonad/xmonad-contrib/issues/728

Since 3fc830aa09368dca04df24bf7ec4ac817f2de479, scratchpads are now added in namedScratchpadManageHook. This, however, means that we need some kind of MapRequestEvent to happen before processing scratchpads, otherwise the manageHook didn't run yet and our extensible state is being left empty. When trying to open a scratchpad right after starting xmonad—i.e., before having opened a window—this may not be the case.

Here is a small config to reproduce the problem. When first starting up xmonad, pressing M-m does not do anything since we haven't opened a window yet. After, e.g., spawning a terminal everything works.

import XMonad
import XMonad.StackSet
import XMonad.Util.EZConfig (additionalKeysP)
import XMonad.Util.NamedScratchpad

main :: IO ()
main = xmonad $ def
  { manageHook = manageHook def <> namedScratchpadManageHook scratchpads }
 `additionalKeysP` [("M-m", namedScratchpadAction scratchpads "xterm")]

scratchpads :: [NamedScratchpad]
scratchpads =
  [NS "xterm"
      "xterm"
      (className =? "XTerm")
      (customFloating $ RationalRect (1 / 6) (1 / 6) (2 / 3) (2 / 3))]

Checklist

• [x] I've read CONTRIBUTING.md

• [x] I've considered how to best test these changes (property, unit, manually, ...) and concluded: Tested it manually and it at least works for me. @exorcist365

• [n/a] I updated the CHANGES.md file

  Don't think this is necessary.

[exorcist365]

Thank you!

[exorcist365]

It does indeed work.