No horizontal scrollbar in XML editor

[Axelboldt]

Using .43 on Windows.

The Attribute/Value window in the XML editor sometimes
lacks a horizontal scrollbar if the displayed value is
too long.

Specifically, bring up the XML editor and select a node
whose value is short enough to fit into the
Attribute/Value window. No horizontal scrollbar is
shown, which is correct. Now select a node whose value
does not fit into the Attribute/Value window. No
horizontal scrollbar is shown, which is wrong. Dragging
a corner of the XML editor window a little bit will
bring up the horizontal scrollbar.

[Kees Cook (kees)]

I can reproduce this by clicking from a node that does not
need the scrollbar to one that does. After the click, the
scrollbar stays missing until a resize event happens.

[su_v (suv-lp)]

No longer reproduced with dockable XML Editor in current trunk (see bug #940715): the horizontal scrollbar now is shown when needed.

(tested with r12168 using docked, detached and floating dialog (prefs))