Clears the contents of a custom dialog window.
Removes all elements inside the dialog.
dlg_clear(handle)
Clear all elements inside an existing dialog
dlg_clear("dialog_123");
dlg_new dlg_init dlg_update dlg_clear
dlg_show dlg_abort
dlg_is_valid dlg_keep_open dlg_callback
dlg_modal dlg_set_resizable dlg_set_pos dlg_set_size dlg_set_btn dlg_set_name dlg_set_color