Textboxes cursor incorrectly positioned when using SFML Renderer

[GoogleCodeExporter]

Steps to reproduce:

1- Use Linux (Ubuntu in my case)
2- Run monodevelop and load GWEN dotnet solution from the SVN build
3- Compile (using DLLMAPS as appropriate)
4- Solve the null sfFont bug (follow steps from #)
5- Fix the default missing fonts bug (Motorwerk, etc... paths are not Linux 
friendly) at line 109 with the following workaround (set the Arial.ttf path as 
appropriate):

try
{
sfFont = new global::SFML.Graphics.Font(font.FaceName);
}
catch (LoadingFailedException)
{
sfFont = new global::SFML.Graphics.Font("/full/path/to/any/font/Arial.ttf");
}

6- Finally, run the SFML Sample application and check the Textbox unit test.

All the textboxes have their writing cursor shifted several positions or lines 
from their true position. I mean, from the position where the cursor blinks, it 
writes several positions behind.

Original issue reported on code.google.com by davigoch...@gmail.com on 5 Nov 2013 at 10:03

[GoogleCodeExporter]

The link I forgot in step 4 is #3 at 
https://code.google.com/p/gwen-dotnet/issues/detail?id=29

Original comment by davigoch...@gmail.com on 5 Nov 2013 at 10:05