难题：关于手写中出现的CEdit焦点问题

|----------------------------------------------------|
|                                                    |
|  -------------------                               |
|  |      CEdit      |                               |
|  -------------------                               |
|                                                    |
|  --------------------   -----------                |
|  |                  |   | CButton |   ...          |
|  |                  |   -----------                |
|  |     手写区       |   ...                        |
|  |                  |   ...                        |
|  |                  |   ...                        |
|  --------------------                              |
|                                                    |
|                                                    |
|                                                    |
|----------------------------------------------------|界面如上，请问如何在写字、点击按钮的时候，让CEdit不失去焦点？高手指教！！