bug#16475: enhancement request: remove vertical scroll bar automatically when not needed

[Keith David Bershatsky]

Resending/forwarding message to the correct tracking number; i.e., it should 
have been 16475 instead of 28936.

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> Subject: 
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> enhancement request: remove vertical scroll bar automatically when not needed
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> Date: 
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> Tue, 24 Oct 2017 20:46:06 -0700
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> Here is a first draft with a simple test (modifying xdisp.c), which probably 
> nukes more than just the selected window's scroll bars when removing them, but 
> it may be sufficient to revive this enhancement request in the event anyone is 
> interested.
>
>  finish_scroll_bars:
>
>    if ((WINDOW_HAS_VERTICAL_SCROLL_BAR (w) || WINDOW_HAS_HORIZONTAL_SCROLL_BAR 
> (w))
>         && ZV - BEGV > BUF_Z (XBUFFER (w->contents)) - w->window_end_pos - 
> marker_position (w->start))
>     {
>       if (WINDOW_HAS_VERTICAL_SCROLL_BAR (w))
>         /* Set the thumb's position and size.  */
>         set_vertical_scroll_bar (w);
>
>       if (WINDOW_HAS_HORIZONTAL_SCROLL_BAR (w))
>         /* Set the thumb's position and size.  */
>         set_horizontal_scroll_bar (w);
>
>       /* Note that we actually used the scroll bar attached to this
>          window, so it shouldn't be deleted at the end of redisplay.  */
>       if (FRAME_TERMINAL (f)->redeem_scroll_bar_hook)
>         (*FRAME_TERMINAL (f)->redeem_scroll_bar_hook) (w);
>     }
>     else
>       {
>         (*FRAME_TERMINAL (f)->condemn_scroll_bars_hook) (f);
>         (*FRAME_TERMINAL (f)->judge_scroll_bars_hook) (f);
>       }
>
>
> Keith
>
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