CurrentValue can be used to poll the state of numerous system values such as the mouse position. Its help page doesn't list all possible items, though. An item like "TooltipFontFamily" isn't listed but it works nevertheless:
In[49]:= CurrentValue["TooltipFontFamily"] Out[49]= "Segoe UI" My question is: where can I find a (more) complete list of items that can be used with CurrentValue. Or, alternatively, how could I programmatically generate such a list?
EDIT
Based on John Fultz' answer I wrote the following:
Union[ Flatten[ Cases[ Import[#], HoldPattern[CurrentValue[a_]] :> a, Infinity ] & /@ FileNames[#] & /@ { FileNameJoin[{$InstallationDirectory, "SystemFiles", "FrontEnd", "StyleSheets", "*.nb"}], FileNameJoin[{$InstallationDirectory, "SystemFiles", "FrontEnd", "TextResources", "*.nb"}], FileNameJoin[{$InstallationDirectory, "SystemFiles", "FrontEnd", "SystemResources", "*.nb"}] }, 2 ] ] and got this:
(* ==> {CommandKey, ControlKey, ControlsFontFamily, ControlsFontSize, DefaultButtonSize, DefaultNewGraphics, HyperlinkModifierKey, LicenseValid, MenuFontFamily, MouseButtonTest, MouseClickCount, MouseOver, NotebookSelected, OptionKey, PanelBackground, PanelFontFamily, PanelFontSize, ScreenArea, ShiftKey, ToolbarBackground, TooltipFontFamily, TooltipFontSize, TooltipFrameMargins, Enabled, Language, {ControlsFontSize, Large}, {ControlsFontSize, Medium}, {ControlsFontSize, Small}, {SystemColor, DialogText}, {SystemColor,DialogTextDisabled}, {SystemColor, MenuText}, {SystemColor, Tooltip}, {SystemColor, TooltipFrame}, {SystemColor, TooltipText}, {TaggingRules, Highlight}, {ScreenRectangle, 1, 2}, {ScreenRectangle, 2, 2}} *) in addition to a message complaining about:
Syntax::sntufn: Unknown unicode longname NumberComma. Other items known by CurrentValue (not in the list above) that were used in answers/comments here:
As per this commentthis comment by celtschk:
{"Thickness", "Opacity", "Dashing", "FontFamily", "FontSize", "FontSlant", "FontWeight", "FontColor", "FontOpacity"}
