cropped variable list in history settings->add active variables

[Jonas A. Krieger]

If the list of history events is too long, the dlgAddVars owerflows and does not allow to select some of the events.

Proposed solution:
add an overflow and max-height style rule to /resources/hs_edit.html :

193: <div class="dlgPanel">
194: <div style="overflow:auto;max-height:90vh;">
195: <table class="mtable subStatusTable" id="event_tags">

[Stefan Ritt]

This problem has been fixed more generally by allowing the whole window to scroll if there is a very long dialog box. This has been fixed in controls.js, so it also applies for all other dialog boxes.