I have found the reply myself. Excuse me for the hasty question. The method is to switch on the mode to control the mouse pointer with the help of keyboard: LeftShift+LeftAlt+NumLock. Select the mode of control the mose pointer. Then with the help of numeric pad and move the mouse pointer to the splitter bar. The pointer changes his view to the double ended arrow and the button "0" ( or the "Ins") emulate the hold down left buttton of the mouse. Enjoy the split bar position!
Thanks for all!
Sincerely yours,
Sergey Kazakov,
Saint-Petersburg,
Russia.