Someone needs to give points to Christoper Willems post.
The Windows 7 and 8 On-Screen Keyboard does not work together with the ABAP Edit Control. Backspace and cursor keys are working but no other keys. The behavior of the Windows On-Screen Keyboard had changed and the ABAP Edit Control was not adopted to this change.
Core patch 6 for the SAP GUI for Windows corrects the problem described. This patch is scheduled for release on September 20, 2013.
Cheers,
Dan Mead