Re: Hope tabulated-list header can be moved via horizontal-scroll-bar

[Juri Linkov]

>>> Emacs tabulated-list is very similar to dataGridView control in WinForm, 
>>> but the list header can not be moved
>>> via horizontal-scroll-bar, which prevents some tabulated-lists (that have 
>>> many columns) from being placed on
>>> the side bar.
>>>
>>> Hope tabulated-list header can be moved via horizontal-scroll-bar in the 
>>> future or anyone know about
>>> alternatives?
>>
>> This needs to be implemented in the display code.  Currently, mode
>> line and header line are not scrolled horizontally with the text
>> (header line is the basis for implementation of tabulated-lists).
>> Conceptually, scrolling in Emacs moves the viewport, not the text, and
>> header line is considered to be part of the viewport.
>>
>> If we do implement that, it should probably be a special minor mode,
>> since not every header line should scroll with the text.  Patches
>> welcome.
>
> 'proced' can scroll the header line.

Actually 'proced' relies on the hack in 'proced-header-line'
that subtracts the amount of 'window-hscroll' columns.
Apparently this line

  (add-hook 'post-command-hook #'force-mode-line-update nil t)  ;; FIXME: Why?

was intended to update the header-line after horizontal scrolling,
but it works correctly even without this hook.

BTW, there is an obsolete function 'tabulated-list-window-scroll-function',
but probably it's unrelated.