Question

c#winform点击菜单时只显示一个子窗体，代码怎么写

多次点击菜单时只显示一个子窗体，不会是显示多个

Answer 1

bool opened = false;
foreach(Form f in Application.OpenForms)
{
if(f is MyForm)
{ opened = true;
break;
}
}
if(!opened)
new MyForm().Show()