Add system scroll-acceleration property

include/boo/IWindow.hpp

@@ -55,6 +55,7 @@ struct SScrollDelta
 {
     double delta[2];
     bool isFine; /* Use system-scale fine-scroll (for scrollable-trackpads) */
+    bool isAccelerated = false; /* System performs acceleration computation */
 
     SScrollDelta operator+(const SScrollDelta& other)
     {return {{delta[0] + other.delta[0], delta[1] + other.delta[1]}, isFine || other.isFine};}

lib/mac/WindowCocoa.mm

@@ -819,7 +819,7 @@ static inline boo::EMouseButton getButton(NSEvent* event)
     boo::SScrollDelta scroll =
     {
         {(float)[theEvent scrollingDeltaX], (float)[theEvent scrollingDeltaY]},
-        (bool)[theEvent hasPreciseScrollingDeltas]
+        (bool)[theEvent hasPreciseScrollingDeltas], true
     };
     booContext->m_callback->scroll(coord, scroll);
     [textContext handleEvent:theEvent];