I want to make simple Yes/No choiced MessageBox, but I think it is nonsense to design a form for that. I thought I could use MessageBox, add buttons, etc. to accomplish this
MessageBox.Show(title, text, messageboxbuttons.yes/no)
This returns a DialogResult which you can check.
For example,
if(MessageBox.Show("","",MessageBoxButtons.YesNo) == DialogResult.Yes) { //do something }