This works with the GDB debugger integration (though it uses GDB's Python pretty printing interface to do it, so well, it works as well as GDB works). Debug > Debugger Options... > GDB Options > Enable Python pretty printing > ON.
There is no support for this built into the LLDB debugger or WinDBG. We do have plans to provide a mechanism within Slickedit for pretty-printing variables (which would allow us to abandon GDB's horrid implemention).