Core v6.4.0

Changes

• Added button xeditor.highContrast which will enable/disable high contrast mode
• Improved short cut handling in order to properly handle combination of CTRL, SHIFT and ALT key

Bugfixes

• History now ensures for attributes to be tracked in every condition by always holding one initial history entry that may be empty to store actions outside of prepare/commit
• Fixed issue causing attributes to be set to null when undo action was performed and would have removed an