Change mouse cursor when over widgets' action spots

[jorgemcpaulo]

For example to indicate where to start dragging

wxWidgets: wxSetCursor(wxCURSOR_HAND);

Qt: setCursor(Qt::OpenHandCursor)

[jorgemcpaulo]

There was a previous attempt:

xvWidgets/src/Widget.cpp

Line 75 in d8dd1a7

void Widget::onMouseMove(const gui_point_t& point)