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.cc

@@ -0,0 +1,44 @@
+#include "MouseWheelSlider.h"
+
+#include <iostream>
+
+
+MouseWheelSlider::MouseWheelSlider( const int x, const int y, const int w, const int h,
+		const char *const l )
+	: Fl_Value_Slider( x, y, w, h, l )
+{
+
+	step( 1 );
+}
+
+int
+MouseWheelSlider::handle( const int event )
+{
+	switch( event )
+	{
+		case FL_MOUSEWHEEL:
+		{
+			// Negative, because I use this for the Brightness control.
+			const int dy= -Fl::event_dy();
+
+			const int newVal= value() - dy * step();
+			if( 0 ) std::cerr << "newVal: " << newVal << " max: " << maximum() << " min: " << minimum() << std::endl;
+			if( newVal >= maximum()
+					and newVal <= minimum() )
+			{
+				value( newVal );
+			}
+
+			do_callback();
+
+			return 1;
+		}
+		break;
+
+		default:
+		{
+			return this->Fl_Value_Slider::handle( event );
+		}
+		break;
+	}
+}