Please, find attached a sample that will help you get started with the RadContextMenu customization. Search for the word "NOTE" to view some explanational notes.
In order to change the width of the column reserved for the icons , you should use the IconColumnWidth property of RadContextMenu. If you want to change the background, you will need to edit the relevant template and inside find the Grid that represents the icon column. Or simply change the MenuPopupIconsBackground brush.
On the other hand , if you want to make cusotmizations on the RadMenuItems in terms of colors and sizes, you need to keep in mind that there are four types of templates for RadMenuItem - ToplLevelItem, TopLevelHeaderItem, SubMenuItem, SubMenuHeaderitem. For more details, please check here and here.
I hope this helps.
Kind regards,
Dani
the Telerik team
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