bring modal or floating windows to front

README.md

@@ -191,8 +191,19 @@ layouts, monocle and tabbed alike: with one window filling the area there is
 nothing for a border to separate it from. Floating windows keep theirs.
 
 In every layout a newly mapped window goes to the front of the arrangement
-order — the first master slot — and takes focus, as in dwm. A window spawned
-onto a tag nobody is viewing leaves both the order and focus alone.
+order — the first master slot — and takes focus, as in dwm. A floating or
+fullscreen window is not part of the arrangement, so it stays where it is, but
+it takes focus like any other new window. A window spawned onto a tag nobody is
+viewing leaves both the order and focus alone.
+
+**Dialogs.** A window that names a parent — a dialog, a file picker — starts
+floating, which `float_children` turns off. Floating windows are stacked by
+focus, but a window and its parents and children are stacked as one family: the
+family rises together on the most recent focus any of its members has had, and
+within it a child is always drawn directly above its parent. Without that, a
+click on the parent of a *modal* dialog would bury the dialog behind the one
+window that will not answer, with no way to raise it again. A dialog opened by
+a fullscreen window is drawn above the fullscreen layer for the same reason.
 
 **tabbed** — same geometry as monocle, minus a strip at the top where att_wm
 draws one tab per window, the focused one highlighted. Each tab is clickable and