> Dragging on empty space in the tab line does not resize windows.  This
 > is unlike the behavior when dragging on empty space in the mode line or
 > in the header line.

I attach a patch for this that hopefully does not negatively affect
'tab-line-mouse-move-tab'.  Juri will have to check.

 > Additionally, hovering the mouse pointer over empty space on the the
 > header line, while it does resize the window, does not display the
 > "resize up down" icon.  This behiavor is differnt from when you hover
 > the mouse pointer over the empty space on the mode line.

I suppose this will have to be done separately when specifying a header
line format (like, for example, 'ruler-mode' does).

martin