Reported on this forum thread: GridPanel with Row Editor Horizontal Scroll when RTL is true.
Sencha issue: Problem with grid roweditor in extjs 5.1.0 => RTL - open since December 2014.
Tested on Ext.NET 3.3.0 and 4.0.0-beta using test case provided on Ext.NET forum thread above and issue happens on both.
IE11 is not affected by the issue.
IE11: works fine.
Chrome 48: scrolls in the opposite direction!
Firefox 44: does not scroll at all!
Safari 9.0.3 (11601.4): scrolls in the opposite direction! Same as Chrome 48 above.
Edge 25: works fine. Same as IE11.
Update: Issue still open after ExtJS 6.0.2 release.
It seems this issue is no longer actual at least with ExtJS 6.0.2: http://jsfiddle.net/fabricio_object/bvezfspy/3/ (this information was added to the Sencha thread)
It may be the case that it was fixed in upcoming ExtJS 5.1.3? Still actual on 5.1.2.
There is a workaround for Ext.NET v3 suggested here:
Update: Issue still open after ExtJS 6.2.1 release.
Tested with Ext.NET 4.2.0, issue still reproducible.
The issue is fixed if the grid view has also RTL specified as true. In other words:
<ext:GridPanel runat="server" RTL="true">
<ViewConfig runat="server" RTL="true" />
Is required in order for RTL horizontal scrolling to work with the grid regardless of using the row editing plugin or not.