[ 1602455 ] [docs] Fix docs for event used by pickers & collapsiblepane

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@43659 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/dirpicker.tex

@@ -46,6 +46,9 @@ The text control is automatically synchronized with button's value. Use function
 
 \wxheading{Event handling}
 
+To process a directory picker event, use these event handler macros to direct input to member
+functions that take a \helpref{wxFileDirPickerEvent}{wxfiledirpickerevent} argument.
+
 \twocolwidtha{7cm}%
 \begin{twocollist}\itemsep=0pt
 \twocolitem{{\bf EVT\_DIRPICKER\_CHANGED(id, func)}}{The user changed the