[MonoDevelop] Font size change in monodevelop

[Robert Trent]

In the MD gui I have defined a label with use_markup = true to enlarge 
its text.  It works!  Now, at run-time, I can change the text but the 
markup has no effect.  I understand that gtk-label has pango, markup 
capability but it is not recognized in my code nor do I find it as a 
label property or method.  lblClientDetailTime.Text = "<big>Now is the 
time</big>"; prints exactly as shown.  Various versions of ~set_markup 
report the label as unknown in this context.  Can someone suggest how I 
might cause the text to enlarge?  My reading on pango has been unfruitful.