Simple SDI splitter, vertical and horizontal for tree windows.
I forget this correction from zip:
case WM_MOUSEMOVE:
if (abs(LOWORD(lParam)- uDragV) < 5)
SetCursor(LoadCursor(NULL, IDC_SIZEWE));
else if (abs(HIWORD(lParam)- uDragH) < 5)
SetCursor(LoadCursor(NULL, IDC_SIZENS));
else SetCursor(LoadCursor(NULL, IDC_ARROW));