Multi selection about listdlg

Hi there, when I use 'listdlg' to do the multi-selection, the only 2 ways I've found is either by push the 'select all' button, or by push the Ctrl+choice1+choice2, what I want is multi-select choice1 and choice2 just by left-clicking mouse, not by push the Ctrl button. I wonder if anyone can give me some advice on my problem, many thanks!