Make XMonad screen setup adapt to connected monitors

- Match scratchpads by WM_CLASS instead of title, so they no longer
  get shifted to workspace 1 or lose track of their window
- Spawn one xmobar per connected screen (dynamicEasySBs)
- Pick the xrandr layout and tray monitor based on whether HDMI is
  connected, and re-run it on monitor hotplug
- Don't let one failed startup step block the rest
- Make the startup command safe to re-run (no duplicate trayer/picom)

.config/xmonad/xmonad.hs

@@ -3,6 +3,7 @@
 import Data.Default
 import Data.Monoid
 import Graphics.X11.ExtraTypes.XF86
+import Control.Monad (liftM2)
 import XMonad
 import XMonad.Actions.PhysicalScreens
 import XMonad.Hooks.DynamicLog
@@ -11,6 +12,7 @@ import XMonad.Hooks.FloatConfigureReq
 import XMonad.Hooks.InsertPosition
 import XMonad.Hooks.ManageDocks
 import XMonad.Hooks.ManageHelpers
+import XMonad.Hooks.Rescreen
 import XMonad.Hooks.StatusBar
 import XMonad.Hooks.StatusBar.PP
 import XMonad.Layout.Grid
@@ -36,7 +38,8 @@ main =
   xmonad
     . ewmhFullscreen
     . ewmh
-    . withEasySB (xmobar1 <> xmobar2) defToggleStrutsKey
+    . dynamicEasySBs myStatusBars
+    . addRandrChangeHook (spawn myScreenHotplug)
     $ myConfig
 
 -- Variables
@@ -68,29 +71,46 @@ myScreenshotDir = "/home/fuxino/Pictures/Screenshots/"
 myScreenshotName :: String
 myScreenshotName = "Screenshot-%Y-%m-%d-%H%M%S.png"
 
+-- Sets up the outputs and the wallpaper, and leaves the tray's monitor in $tray
+myScreenLayout :: String
+myScreenLayout =
+  "if xrandr --query | grep -q '^HDMI-1-0 connected'; then"
+    ++ " xrandr --output HDMI-1-0 --preferred --primary --output eDP-1 --right-of HDMI-1-0 --preferred; tray=1;"
+    ++ " else xrandr --output eDP-1 --preferred --primary --output HDMI-1-0 --off; tray=0; fi"
+    ++ "; ~/.fehbg"
+
+-- Replaces any running trayer, so there's never more than one
+myTrayer :: String
+myTrayer =
+  "pkill -x trayer; while pgrep -x trayer > /dev/null; do sleep 0.1; done; \
+  \trayer -l --edge top --align right --SetDockType true \
+  \--SetPartialStrut true --expand true --widthtype request \
+  \--tint 0x232634 --height 18 --monitor $tray"
+
+-- Safe to re-run (e.g. spawnOnce after this string changes and xmonad restarts)
 myScreenSetup :: String
 myScreenSetup =
-  "sleep 1 && xrandr --output HDMI-1-0 --preferred --primary --output eDP-1 --right-of HDMI-1-0 --preferred && ~/.fehbg"
+  "sleep 1; " ++ myScreenLayout ++ "; pgrep -x picom > /dev/null || picom -b -c; " ++ myTrayer
-    ++ " && picom -b -c"
+
-    ++ " && trayer -l --edge top --align right --SetDockType true \
+-- Run when a monitor is (dis)connected; restarts trayer so it moves to the right screen
-       \--SetPartialStrut true --expand true --widthtype request \
+myScreenHotplug :: String
-       \--tint 0x232634 --height 18 --monitor 1"
+myScreenHotplug = myScreenLayout ++ "; " ++ myTrayer
 
 myScratchpads :: [NamedScratchpad]
 myScratchpads =
   [ NS "Riseup-vpn" "riseup-vpn" (className =? "RiseupVPN") (customFloating $ W.RationalRect 0.15 0.4 0.15 0.4),
-    NS "Terminal" spawnTerminal (title =? "kitty-float") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6),
+    NS "Terminal" spawnTerminal (className =? "scratch-terminal") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6),
-    NS "Music" spawnMusic (title =? "ncmpcpp") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6),
+    NS "Music" spawnMusic (className =? "scratch-music") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6),
-    NS "Mail" spawnMail (title =? "mutt") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6),
+    NS "Mail" spawnMail (className =? "scratch-mail") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6),
-    NS "Cal" spawnCal (title =? "calcurse") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6),
+    NS "Cal" spawnCal (className =? "scratch-cal") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6),
-    NS "Btop" spawnBtop (title =? "btop") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6)
+    NS "Btop" spawnBtop (className =? "scratch-btop") (customFloating $ W.RationalRect 0.2 0.2 0.6 0.6)
   ]
   where
-    spawnTerminal = myTerminal ++ " -T kitty-float"
+    spawnTerminal = myTerminal ++ " --class scratch-terminal -T kitty-float"
-    spawnMusic = myTerminal ++ " -T ncmpcpp ncmpcpp"
+    spawnMusic = myTerminal ++ " --class scratch-music -T ncmpcpp ncmpcpp"
-    spawnMail = myTerminal ++ " -T mutt bash -c 'pushd ~/Downloads > /dev/null; mutt; popd > /dev/null'"
+    spawnMail = myTerminal ++ " --class scratch-mail -T mutt bash -c 'pushd ~/Downloads > /dev/null; mutt; popd > /dev/null'"
-    spawnCal = myTerminal ++ " -T calcurse calcurse"
+    spawnCal = myTerminal ++ " --class scratch-cal -T calcurse calcurse"
-    spawnBtop = myTerminal ++ " -T btop btop"
+    spawnBtop = myTerminal ++ " --class scratch-btop -T btop btop"
 
 -- Config
 myConfig =
@@ -105,7 +125,8 @@ myConfig =
       manageHook = myManageHook,
       handleEventHook = myHandleEventHook
     }
-    `additionalKeysP` [ ("M-S-l", spawn "slock"),
+    `additionalKeysP` [ ("M-b", sendMessage ToggleStruts),
+                        ("M-S-l", spawn "slock"),
                         ("<Print>", unGrab *> spawn ("scrot " ++ myScreenshotDir ++ myScreenshotName)),
                         ("S-<Print>", unGrab *> spawn ("scrot -s " ++ myScreenshotDir ++ myScreenshotName)),
                         ("M-S-<Print>", unGrab *> spawn ("scrot -u " ++ myScreenshotDir ++ myScreenshotName)),
@@ -164,9 +185,13 @@ myLayoutHook = onWorkspace "2:\xe743 " myWebLayout $ onWorkspace "3:\xf1b6 " myG
     delta = 3 / 100
 
 -- Xmobar
-xmobar1 = statusBarProp "xmobar -x 0 ~/.config/xmobar/xmobarrc_hdmi" (pure myXmobarPP)
+-- One bar per connected screen. The laptop config leaves room for trayer, so it
-
+-- goes on the laptop screen, which is screen 1 with HDMI and screen 0 without.
-xmobar2 = statusBarProp "xmobar -x 1 ~/.config/xmobar/xmobarrc_laptop" (pure myXmobarPP)
+myStatusBars :: ScreenId -> X StatusBarConfig
+myStatusBars (S i) = do
+  nScreens <- gets (length . W.screens . windowset)
+  let rc = if nScreens > 1 && i /= 1 then "xmobarrc_hdmi" else "xmobarrc_laptop"
+  pure $ statusBarProp ("xmobar -x " ++ show i ++ " ~/.config/xmobar/" ++ rc) (pure myXmobarPP)
 
 myXmobarPP :: PP
 myXmobarPP =
@@ -211,6 +236,7 @@ myStartupHook = do
   spawnOnce "blueman-applet"
   spawnOnce "mousemove"
   spawnOnce "adb start-server"
+  spawnOnce "/home/fuxino/.local/bin/discover-overlay-wait"
 
 -- Manage hook
 myManageHook :: ManageHook
@@ -236,8 +262,8 @@ myManageHook =
       className =? "libreoffice-calc" --> doShift "6:\xeb69 ",
       className =? "libreoffice-writer" --> doShift "6:\xeb69 ",
       className =? "mpv" --> doFullFloat,
-      className =? "mpv" --> doShift "5:\xead9 ",
+      className =? "mpv" --> viewShift "5:\xead9 ",
-      className =? "FreeTube" --> doShift "5:\xead9 ",
+      className =? "freetube" --> doShift "5:\xead9 ",
       className =? myTerminal --> doShift "1:\xf489 ",
       className =? "scrcpy" --> doShift "5:\xead9 ",
       className =? "steam" --> doShift "3:\xf1b6 ",
@@ -254,6 +280,7 @@ myManageHook =
       isFullscreen --> doFullFloat
     ]
     <+> namedScratchpadManageHook myScratchpads
+    where viewShift = doF . liftM2 (.) W.greedyView W.shift
 
 -- Handle event hook
 myHandleEventHook :: Event -> X All