Re: Window splitting issues with margins

[martin rudalics <rudalics@gmx.at>]

 > Columns
 > that have such an associated SYM property are not considered reducible
 > by `window-splittable-p'.

As I tried to explain before: ‘window-splittable-p’ is hardly the
function we care about here.  We care about ‘split-window’ itself.

 > It would still have to be possible for modes like writeroom-mode to set
 > the margin to a specific width without setting a property, but those
 > margins would be considered reducible by `window-splittable-p'.
 > Furthermore, it shouldn't be possible to set a width that is smaller
 > than what other modes have set. This could either be enforced by the API
 > or writeroom-mode would have to ensure this itself.

There are two issues involved:

(1) ‘linum-mode’ sets the margin to some small, fixed value defeating
‘writeroom-mode’.  I think this can be fixed by having ‘writeroom-mode’
set a ‘margins-min-width’ window parameter and have either
‘set_window_margins’ or modes like ‘linum-mode’ respect that value.

(2) When a window is split via ‘split-window-right’ or is shrunk
horizontally, ‘writeroom-mode’ probably should reset its margins (and
the window parameter) to some lower value.  It should do that via
‘window-configuration-change-hook’ (when splitting) and
‘window-size-change-functions’ (when the window is resized).  When the
splitting is undone or the window is sized back, ‘writeroom-mode’ will
probably want to enlarge the margins again.

martin