In the Qt documentation about signals and slots they say:quote:Callbacks have two fundamental flaws: Firstly, they are not type-safe. We can never be certain that the processing function will call ...

So, a couple thoughts:<BR>1- have you tried both methods of function parameter layouts in the C callback function (pascal and stdcall)?<BR>2- could you make the C code C++, add an interface into ...

However, in C you have to define a function by name and pass a pointer — not a huge problem, but it can get messy if you have a lot of callback functions that you use only one time.