I dunno that this makes it any easier...

I tried splitting up the sources to speed
up some compiling... but it didn't help.
I dunno that it's more readable this way.

I'm checkpointing this just in case.

MouseWheelSlider.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <Fl/Fl.H>
+#include <Fl/Fl_Window.H>
+#include <Fl/Fl_Value_Slider.H>
+
+class MouseWheelSlider : public Fl_Value_Slider
+{
+	public:
+		explicit MouseWheelSlider( const int x, const int y, const int w, const int h, const char *const l= 0 );
+
+		int handle( const int event ) override;
+};