[Q] How to display a custom dialog with LrDialogs.presentModalDialog and only *one* close button

I’m writing a Lightroom Classic plugin with lua, which generally works quite well.

However, I have an issue with a very fundamental thing:

Displaying an error dialog that simply has a single close button.

No matter what  I try, at least on my Mac I always get an OK and Cancel button.

What am I doing wrong?

LrDialogs.presentModalDialog{
   title = Global.moduleName,
   contents = myContent
}

Thanks
 

Klaus