WPF: Finally fixed the bug where the WaveFormCacheService would not return the right tiles at lower zoom levels. This makes the wave form bitmap refresh when zooming in as smooth as Google Maps. There's still a bug that creates some black areas (probably when refreshing a tile that's been generated), but this makes a HUGE difference. Also fixed bug in WaveFormControl where the bitmap tile original content offset x would not be respected (related to previously described bug).