DELPHI判断创建动态窗体函数，已存在则直接显示

//==============================================================================
// if mark=0 then Tform.show else Tform.showmodal
//==============================================================================

procedure OpenChildForm(FormClass:TFormClass;var Form:TForm;Mark:Integer=0);
begin
if Mark=0 then
begin
if not Assigned(form) then Application.CreateForm(FormClass,Form);
if Form.WindowState=wsminimized then Form.WindowState:=wsMaximized;
end else begin
form:=FormClass.Create(nil);
Form.ShowModal;
Form.Free;
end;
end;