Explanation why there is no space between l and other letters

In SSMPropEditor you might notice in the tree view like below that there is no distance between lowercase a and l in Architectural and Electrical but it look just fine with Structural and Mechanical. Why is this happening?

   vs  

Is is apparently normal for GDI+ text based rendering and GDIPlus is used in this treeview control. Here is Microsoft attempt to explain it: http://support.microsoft.com/kb/307208/en-us

What I did to solve this was increasing the font height a little. If you want to be able to edit multiple sheet set properties take a look at SSMPropEditor.