| odd | XMonad.Config.Prime | 
| OffsetLeft | XMonad.Util.Image | 
| offsetRegion | XMonad.Config.Prime | 
| OffsetRight | XMonad.Util.Image | 
| Older | XMonad.Hooks.InsertPosition | 
| on | XMonad.Prelude | 
| onBottom | XMonad.Layout.Drawer | 
| once | XMonad.Util.ExtensibleConf | 
| onceM | XMonad.Util.ExtensibleConf | 
| onClassChange | XMonad.Hooks.OnPropertyChange, XMonad.Hooks.DynamicProperty | 
| onCurr | XMonad.Util.Dzen | 
| onCurrentScreen | XMonad.Layout.IndependentScreens | 
| onDecorationClick | XMonad.Layout.DecorationEx.Common | 
| OneBig |   | 
| 1 (Type/Class) | XMonad.Layout.OneBig | 
| 2 (Data Constructor) | XMonad.Layout.OneBig | 
| oneName | XMonad.Util.NamedActions | 
| oneShotHook | XMonad.Hooks.DynamicHooks | 
| onFocusedZ | XMonad.Util.Stack | 
| onFocusedZM | XMonad.Util.Stack | 
| onGroup | XMonad.Layout.SubLayouts | 
| OnHost | XMonad.Layout.OnHost | 
| onHost | XMonad.Layout.OnHost | 
| onHosts | XMonad.Layout.OnHost | 
| onIndexZ | XMonad.Util.Stack | 
| onIndexZM | XMonad.Util.Stack | 
| onLayout | XMonad.Layout.Groups | 
| onLeft | XMonad.Layout.Drawer | 
| onLogger | XMonad.Util.Loggers | 
| OnlyFloat | XMonad.Layout.NoBorders | 
| OnlyLayoutFloat | XMonad.Layout.NoBorders | 
| OnlyLayoutFloatBelow | XMonad.Layout.NoBorders | 
| onlyOnScreen | XMonad.Actions.OnScreen | 
| OnlyScreenFloat | XMonad.Layout.NoBorders | 
| onNextNeighbour | XMonad.Actions.PhysicalScreens | 
| onPrevNeighbour | XMonad.Actions.PhysicalScreens | 
| onRight | XMonad.Layout.Drawer | 
| OnScreen | XMonad.Hooks.UrgencyHook | 
| onScreen | XMonad.Actions.OnScreen | 
| onScreen' | XMonad.Actions.OnScreen | 
| onScreens | XMonad.Config.Prime | 
| onTitleChange | XMonad.Hooks.OnPropertyChange, XMonad.Hooks.DynamicProperty | 
| onTop | XMonad.Layout.Drawer | 
| onWorkspace | XMonad.Layout.PerWorkspace | 
| onWorkspaces | XMonad.Layout.PerWorkspace | 
| onXPropertyChange | XMonad.Hooks.OnPropertyChange, XMonad.Hooks.DynamicProperty | 
| onZipper | XMonad.Layout.Groups | 
| Opacity | XMonad.Hooks.FadeWindows | 
| opacity |   | 
| 1 (Function) | XMonad.Hooks.FadeWindows | 
| 2 (Function) | XMonad.Layout.Monitor | 
| opaque | XMonad.Hooks.FadeWindows | 
| openDisplay | XMonad.Config.Prime | 
| OpenPunctuation | XMonad.Prelude | 
| openstreetmap | XMonad.Actions.Search | 
| operationOn | XMonad.Config.Dmwit | 
| option | XMonad.Util.Parser | 
| optional | XMonad.Prelude | 
| optionally | XMonad.Util.Parser | 
| Or | XMonad.Util.WindowProperties, XMonad.Layout.SortedLayout, XMonad.Layout.IM, XMonad.Layout.Drawer, XMonad.Layout.Monitor, XMonad.Layout.ComboP | 
| or | XMonad.Prelude, XMonad.Config.Prime | 
| Ord | XMonad.Config.Prime | 
| ord | XMonad.Prelude | 
| Ordering | XMonad.Config.Prime | 
| OrgMode | XMonad.Prompt.OrgMode | 
| orgPrompt | XMonad.Prompt.OrgMode | 
| orgPromptPrimary | XMonad.Prompt.OrgMode | 
| orgPromptRefile | XMonad.Prompt.OrgMode | 
| orgPromptRefileTo | XMonad.Prompt.OrgMode | 
| Orientation |   | 
| 1 (Type/Class) | XMonad.Layout.HintedTile | 
| 2 (Type/Class) | XMonad.Layout.GridVariants | 
| orientation | XMonad.Layout.HintedTile | 
| orIfPrefixed | XMonad.Actions.Prefix | 
| origin | XMonad.Util.History | 
| OrigWin | XMonad.Layout.Decoration | 
| OtherIndicated | XMonad.Layout.NoBorders | 
| OtherLetter | XMonad.Prelude | 
| OtherNumber | XMonad.Prelude | 
| OtherPunctuation | XMonad.Prelude | 
| OtherSymbol | XMonad.Prelude | 
| otherwise | XMonad.Prelude, XMonad.Config.Prime | 
| outputOf | XMonad.Config.Dmwit | 
| overlay | XMonad.Hooks.Modal | 
| overlayedFloatMode | XMonad.Hooks.Modal | 
| overlayedFloatModeLabel | XMonad.Hooks.Modal | 
| overlayF | XMonad.Actions.EasyMotion | 
| ownerGrabButtonMask | XMonad.Config.Prime | 
| OwnFile | XMonad.Util.Run | 
| oxymor00nTheme | XMonad.Util.Themes |