nsIEditorStyleSheets Interface

 load and apply an Override style sheet, specified by aURL, to
 the editor's document, on top of any that are already there.
 IMPORTANT: This is assumed to be synchronous:
            URL is a local file with no @import used
 This action is not undoable.
 It is not intended for use by "user", only editor developers
   to change display behavior for editing (like showing special cursors)
   that will not be affected by loading other "document" style sheets
   loaded using addStyleSheet or replaceStyleSheet.

 @param aURL         The style sheet to be loaded and applied.

void addOverrideStyleSheet(in AString aURL)

 Add the given Style Sheet to the editor's document,
 on top of any that are already there.
 This is always synchronous.

 @param aURL  The style sheet to be  applied.

void addStyleSheet(in AString aURL)

 Enable or disable the given Style Sheet from the editor's document
 This is always synchronous

 @param aURL  The style sheet to be removed

void enableStyleSheet(in AString aURL, in PRBool aEnable)

 Get the nsICSSStyleSheet associated with the given URL.

 @param aURL         The style sheet's URL
 @return             the style sheet

[noscript] nsICSSStyleSheet getStyleSheetForURL(in AString aURL)

 Get the URL associated with the given nsICSSStyleSheet.

 @param aStyleSheet  The style sheet
 @return             the style sheet's URL

[noscript] AString getURLForStyleSheet(in nsICSSStyleSheet aStyleSheet)

 Remove the given Override Style Sheet from the editor's document
 This is always synchronous

 @param aURL  The style sheet to be removed.

void removeOverrideStyleSheet(in AString aURL)

 Remove the given Style Sheet from the editor's document
 This is always synchronous

 @param aURL  The style sheet to be removed

void removeStyleSheet(in AString aURL)

 load and apply the style sheet, specified by aURL, to the
 editor's document, replacing the last style sheet added (if any).
 This is always synchronous.
 
 @param aURL         The style sheet to be loaded and applied.

void replaceOverrideStyleSheet(in AString aURL)

 load and apply the style sheet, specified by aURL, to the
 editor's document, replacing the last style sheet added (if any).
 This can involve asynchronous network I/O.
 
 @param aURL         The style sheet to be loaded and applied.

void replaceStyleSheet(in AString aURL)