Note that scrolled windows send the wxScrollWinEvent which does not derive from wxCommandEvent, but from wxEvent directly - don't confuse these two kinds of events and use the event table macros mentioned below only for the scrollbar-like controls.
The difference between EVT_SCROLL_THUMBRELEASE and EVT_SCROLL_CHANGED
The EVT_SCROLL_THUMBRELEASE event is only emitted when actually dragging the thumb using the mouse and releasing it (This EVT_SCROLL_THUMBRELEASE event is also followed by an EVT_SCROLL_CHANGED event).
The EVT_SCROLL_CHANGED event also occurs when using the keyboard to change the thumb position, and when clicking next to the thumb (In all these cases the EVT_SCROLL_THUMBRELEASE event does not happen).
In short, the EVT_SCROLL_CHANGED event is triggered when scrolling/ moving has finished independently of the way it had started. Please see the page_samples_widgets ("Slider" page) to see the difference between EVT_SCROLL_THUMBRELEASE and EVT_SCROLL_CHANGED in action.
Remark: Note that unless specifying a scroll control identifier, you will need to test for scrollbar orientation with getOrientation/1, since horizontal and vertical scroll events are processed using the same event handler.
wxWidgets docs: wxScrollEvent
scroll_top | scroll_bottom | scroll_lineup | scroll_linedown |
scroll_pageup | scroll_pagedown | scroll_thumbtrack |
scroll_thumbrelease | scroll_changed