C++: Step 4 of the std::string transition. Remove C style string lambda support due to limitations of std::function. std::function due to its template definition cannot differentiate parameters. This causes std::function parameters to be indistiguishable despite different signatures. Use the C style function pointer instead if you want C style strings, not lambdas. Convert KeyPress lambda to use std::string, this was missed in the last commit.

[Desktop Entry]
Name=Dynamic Windows Test
Exec=@prefix@/bin/dwtest 
Terminal=false
MultipleArgs=false
Type=Application
Categories=Application;Development;X-Red-Hat-Base;