[LyX/master] Add comment

[Scott Kostyshak]

commit 82ef95043db2da23c9b802b9922666ac8d34cdc0
Author: Scott Kostyshak <skost...@lyx.org>
Date:   Sun Nov 22 11:21:55 2015 -0500

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diff --git a/src/frontends/qt4/GuiPrefs.cpp b/src/frontends/qt4/GuiPrefs.cpp
index 2c99dee..ef6f263 100644
--- a/src/frontends/qt4/GuiPrefs.cpp
+++ b/src/frontends/qt4/GuiPrefs.cpp
@@ -3355,6 +3355,7 @@ void GuiPreferences::dispatchParams()
 
        if (update_screen_font_) {
                dispatch(FuncRequest(LFUN_SCREEN_FONT_UPDATE));
+               // resets flag in case second apply in same dialog
                update_screen_font_ = false;
        }