° symbol on Mono Linux is not displayed

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http://stackoverflow.com – Our winforms software extensively using ° - degree symbol. Which is &deg or &#176 in ISO/IEC 8859-1 (also known as Latin-1). There is no problem with the symbol on .NET Windows for decent number of fonts (We use about 5 fonts in app). There is no problem with ° on Linux in general. I can see in in Gtk applications, can input °, say, in console if typing ctrl+shift+u-b-0, but not in our Mono application. When we run the software under Mono on Linux (Ubuntu 12.10) the degree symbols are not displayed (black question chars are rendered instead). Is there any way to configure mo (HowTos)