Reduce workspace switching flicker

Previously, workspace switch might flicker a bit upon changing to a
higher number. This could be observed by switching repeatedly between
first and second workspace, for example. 2->1 does not flicker, but 1->2
sometimes shows desktop. This commit fixes the issue: visible workspaces
are first unhidden, and then invisible ones are hidden.

closes nikitabobko#275

Sources/AppBundle/refresh.swift

@@ -68,14 +68,15 @@ private func refreshFocusedWorkspaceBasedOnFocusedWindow() { // todo drop. It sh
 }
 
 private func layoutWorkspaces() {
- for workspace in Workspace.all {
-  if workspace.isVisible {
-  // todo no need to unhide tiling windows (except for keeping hide/unhide state variables invariants)
-  workspace.allLeafWindowsRecursive.forEach { ($0 as! MacWindow).unhideViaEmulation() } // todo as!
-  } else {
-  workspace.allLeafWindowsRecursive.forEach { ($0 as! MacWindow).hideViaEmulation() } // todo as!
- }
+ // to reduce flicker, first unhide visible workspaces, then hide invisible ones
+ for workspace in Workspace.all where workspace.isVisible {
+ // todo no need to unhide tiling windows (except for keeping hide/unhide state variables invariants)
+ workspace.allLeafWindowsRecursive.forEach { ($0 as! MacWindow).unhideViaEmulation() } // todo as!
+ }
+ for workspace in Workspace.all where !workspace.isVisible {
+ workspace.allLeafWindowsRecursive.forEach { ($0 as! MacWindow).hideViaEmulation() } // todo as!
  }
+
  for monitor in monitors {
  monitor.activeWorkspace.layoutWorkspace()
  }