It is not possible to select a Toolbar item in RadFileExplorer on Enter press if the control is used in Lightweight render mode.
Steps to reproduce:
1. Open https://demos.telerik.com/aspnet-ajax/fileexplorer/examples/keyboardsupport/defaultcs.aspx
2. Press "Ctrl+f2" to focus RadFileExplorer
3. Press "Shift+1" to focus its toolbar
4. Use the Arrow keys to navigate between to Toolbar items
5. Press Enter over a button (e.g. Upload)
Result: The command is not triggered
Workaround: The issue is not reproducible in Classic render mode.