I performed a quick test with 100%, 125% and 150% (the standard settings in Windows 7 control panel) and the WPF application UI scaled nicely without breaking the workaround I suggested.
By the way the auto scroll is a "feature" of the standard ScrollViewer in WPF - the standard WPF ComboBox also has it, in lower extent, however, because its dropdown is evenly sized with its items...
the Telerik team
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