[AndyD]

Поменяй

Winapi::sendMessage(theTable.hWnd(), #WM_HSCROLL, 0,'');

на

Winapi::sendMessageEx(theTable.hWnd(), #WM_HSCROLL, #SB_RIGHT, 0);
Winapi::sendMessageEx(theTable.hWnd(), #WM_HSCROLL, #SB_LEFT, 0);