how to custom the dialog when click the menu toolbar

hi,
i have a requirement that i want to custom the dialog when i click the menu in the toolbar .eg. i want to insert a textfield into ckedit,when i click the icon "textfield" in toolbar,a dialog will display.Because of my complex demand,i want to add some controls into the dailog or custom the dialog all by meself.If I will do so.
how can i do?
Thank you for advanced.