[xmonad] How to handle modal dialog windows

[Peter]

Hi
I use the following layout:

myLayout = tiled ||| Mirror tiled ||| Full ||| HintedTile 1 0.1 0.5 
TopLeft XMonad.Layout.HintedTile.Tall
  where
     -- default tiling algorithm partitions the screen into two panes
     tiled   = XMonad.Tall nmaster delta ratio
 
     -- The default number of windows in the master pane
     nmaster = 1
 
     -- Default proportion of screen occupied by master pane
     ratio   = 1/2
 
     -- Percent of screen to increment by when resizing panes
     delta   = 3/100

Some applications like firefox, thunderbird make heavy use of modal 
dialogs, for example to set preferences. These are usually small windows 
that float over the application until you dismiss them.
However, with the layouts I use, those windows get scaled to fill have 
of the screen, left to the application. That is annoying , in particular 
since the control buttons (OK Cancel ) do not appear , so I have to 
force quit that window.
I really like those layouts above for everything (xterm windows, vims , 
etc ) but I would like to  adjust xmonad in order to take into account 
the modal dialogs for the typical GUI Apps.

Any ideas are welcomed
Thanks for help
Peter