Subject: bug#76084: 31.0.50; Dragging tab line does not resize windows, unlike header line or mode line

From: martin rudalics <[email-masked]>
Date: Mon, 10 Feb 2025 11:15:34 +0100

> The code in xdisp.c that updates the mouse icon for dragging the mode
 > line (search for "draggable") is straightforward to adjust to also
 > handle the header and tab lines.  That works for almost all cases, I
 > can confirm it works fine for Info mode, tab-line mode, and
 > window-tool-bar mode.

Can you do that?

 > It doesn't work for ruler-mode still because
 > ruler-mode sets its own binding for <header-line> <down-mouse-1> in
 > its keymap.
 >
 > To handle this I would need to add checks against the down-mouse-1
 > keybinding before setting the mouse icon.  I'm just worried about
 > performance here since looking up the keymap would get run on mouse
 > motion.

I think there's no reason to bother about 'ruler-mode'.  IIRC, apart
from the scroll bar, the ruler has no "empty space" and dragging should
mostly happen in a horizontal fashion.

martin