Yes, for some functions. (only retuning, int or ordinal value / not returning string or managed types / strings work in trunk when using dwarf-3)
Tools > Debugger > General: enable function calling
And enable for each watch individually in its properties.
Should work if the function body is in your code. And in case of methods, in the same unit.
If I try to see the value of C.Res I get a
"Type TCLASS has no component named RES."
Is this dependent on debugger/os/?? or is this not possible in general?
Only with FpDebug (tools > debugger > backend)
On Win 64/32 and Linux 64. (And Linux 32 bit with Lazarus 2.3 main-branch)