Torben,
>>It's in the SqlFileStorage.cs file, I want to trigger these messages.
These messages are supported in SqlFileStorage.cs.
Demo:
If you upload a text file in the image dialog, you will get an error "FileformatNotsupported".
asp.net Chat http://cutesoft.net/ASP.NET+Chat/default.aspx
Web Messenger: http://cutesoft.net/Web-Messenger/default.aspx
asp.net wysiwyg editor: http://cutesoft.net/ASP.NET+WYSIWYG+Editor/default.aspx
asp wysiwyg html editor: http://cutesoft.net/ASP
asp.net Image Gallery: http://cutesoft.net/ASP.NET+Image+Gallery/default.aspx
Live Support: http://cutesoft.net/live-support/default.aspx