Index - O
| oneKb | Graphics.UI.FLTK.LowLevel.Utils | 
| OnExcept | Graphics.UI.FLTK.LowLevel.Fl_Enumerations | 
| Op | Graphics.UI.FLTK.LowLevel.Dispatch, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| Open | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| open | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| OpenAndCallback | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| openAndCallback | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| OpenToggle | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| openToggle | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| OpenToggleAndCallback | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| openToggleAndCallback | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| Option | Graphics.UI.FLTK.LowLevel.FL | 
| option | Graphics.UI.FLTK.LowLevel.FL | 
| OptionalSizeRangeArgs | |
| 1 (Type/Class) | Graphics.UI.FLTK.LowLevel.Window, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| 2 (Data Constructor) | Graphics.UI.FLTK.LowLevel.Window, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| OptionArrowFocus | Graphics.UI.FLTK.LowLevel.FL | 
| OptionDndText | Graphics.UI.FLTK.LowLevel.FL | 
| OptionLast | Graphics.UI.FLTK.LowLevel.FL | 
| OptionShowTooltips | Graphics.UI.FLTK.LowLevel.FL | 
| OptionVisibleFocus | Graphics.UI.FLTK.LowLevel.FL | 
| Orientation | Graphics.UI.FLTK.LowLevel.Fl_Types, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| orNullFunPtr | Graphics.UI.FLTK.LowLevel.Utils | 
| Ortho | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| ortho | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| OshadowBox | Graphics.UI.FLTK.LowLevel.Fl_Enumerations | 
| OutOfRange | |
| 1 (Type/Class) | Graphics.UI.FLTK.LowLevel.Fl_Types, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| 2 (Data Constructor) | Graphics.UI.FLTK.LowLevel.Fl_Types, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| Output | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| outputCustom | Graphics.UI.FLTK.LowLevel.Output, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| Outputfile | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| outputfile | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| OutputfileWithBuflen | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| outputfileWithBuflen | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| outputNew | Graphics.UI.FLTK.LowLevel.Output, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| OvalBox | Graphics.UI.FLTK.LowLevel.Fl_Enumerations | 
| OvalFrame | Graphics.UI.FLTK.LowLevel.Fl_Enumerations | 
| OverlayWindow | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| overlayWindowNew | Graphics.UI.FLTK.LowLevel.OverlayWindow, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| Overstrike | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| overstrike | Graphics.UI.FLTK.LowLevel.Hierarchy, Graphics.UI.FLTK.LowLevel.FLTKHS | 
| ownColormap | Graphics.UI.FLTK.LowLevel.FL |