How to move the parent window in Child window?

Currently, I use:

::SendMessage(GetParent(),WM_NCLBUTTONDOWN,HTCAPTION,0);

to put the parent window in moving and sizing modal, but this has some side effects. so i'm looking for another way to let the pa开发者_如何学运维rent go into the moving and sizing modal.

See WM_SYSCOMMAND. Pass SC_MOVE as the wParam value and 0 or -1 as the lParam value.