scrollintoview for showhide buttons

[xi]

If a user clicks a showhide button there is no guarantee that the box that is to appear is currently scrolled into view. This might especially happen in connection with iframe overlays (#536).

Two fix this it would be great if the showhide javascript code could additionally:

1. scroll so that the appearing box is visible
2. scroll only if the box is currently not visible
3. visibly scroll (instead of jumping to the position) so the user understands what happens

So far I found

• scrollIntoView - standard javascript, but does only meet condition 1
• scrollIntoViewIfNeeded - only webkit; does not meet condition 3
• jquery-scrollintoview - not tested yet

[nidico]

Yeah, this is an actual issue within the iframes. If the jquery plugin works fine, use it, if not use any of the others.

[xi]

This is much less of a problem with the autoresizing introduced later in the iframe pull request (xi/adhocracy@702505a)