bool GetPenDown(); // << ADD THIS
... AND ...
class RectTracker : public LocalLoop {
public:
	virtual void  LeftUp(Point, dword);
	virtual void  RightUp(Point, dword);
	virtual void  MouseMove(Point p, dword);
	virtual bool  Pen(Point p, const PenInfo& pn, dword keyflags); // << ADD THIS

...
	if(findarg(e, LEFTUP, RIGHTUP, MIDDLEUP) >= 0)
		KillRepeat();
	Image result = DispatchMouseEvent(e, p, zd);
	if(!GetMouseRight() && !GetMouseMiddle() && !GetMouseLeft() && !GetPenDown())
		ReleaseCtrlCapture();
	return result;
...

bool RectTracker::Pen(Point p, const PenInfo& pn, dword keyflags){
	switch(pn.action){
		case 0:
			MouseMove(p,keyflags);
			break;
		case PEN_UP:
			EndLoop();
			break;
	}
	return true;
}

...
bool Ctrl::ProcessEvent(bool *quit)
{
	ASSERT_(IsMainThread(), "ProcessEvent can only run in the main thread");
	if(!GetMouseLeft() && !GetMouseRight() && !GetMouseMiddle() && !GetPenDown()) // << HERE
		ReleaseCtrlCapture();
...