Improve the editing in RadSpreadsheet with IME (input method editors). 

Problematic scenarios:

- Start typing:
When Japanese IME is chosen (for example) and the user starts typing while a cell is selected, the CellEditor should be in EditMode - the same behavior as if you are typing in English.

- Committing:
When the user is already in EditMode and typing with the Japanese IME, suggestions are listed in a popup. The user can than commit the sentence by selecting some of the suggested words with the mouse (by double-clicking on the suggestion) everything is correct and you continue to be in EditMode. However, if the user navigates to the suggestion and hit Enter (which is the most used case and it is somehow the native one) the editor goes out from EditMode to Inactive.