Tidied up some comments

modules/juce_audio_utils/gui/juce_AudioThumbnail.h

@@ -78,7 +78,7 @@ public:
         setSource (new FileInputSource (file))
         @endcode
 
-        You can pass a zero in here to clear the thumbnail.
+        You can pass a nullptr in here to clear the thumbnail.
         The source that is passed in will be deleted by this object when it is no longer needed.
         @returns true if the source could be opened as a valid audio file, false if this failed for
         some reason.

modules/juce_audio_utils/gui/juce_AudioThumbnailBase.h

@@ -56,7 +56,7 @@ public:
         setSource (new FileInputSource (file))
         @endcode
 
-        You can pass a zero in here to clear the thumbnail.
+        You can pass a nullptr in here to clear the thumbnail.
         The source that is passed in will be deleted by this object when it is no longer needed.
         @returns true if the source could be opened as a valid audio file, false if this failed for
         some reason.

modules/juce_gui_basics/layout/juce_ResizableCornerComponent.h

@@ -51,10 +51,10 @@ public:
         Remember that when the target component is resized, it'll need to move and
         resize this component to keep it in place, as this won't happen automatically.
 
-        If the constrainer parameter is non-zero, then this object will be used to enforce
+        If a constrainer object is provided, then this object will be used to enforce
         limits on the size and position that the component can be stretched to. Make sure
         that the constrainer isn't deleted while still in use by this object. If you
-        pass a zero in here, no limits will be put on the sizes it can be stretched to.
+        pass a nullptr in here, no limits will be put on the sizes it can be stretched to.
 
         @see ComponentBoundsConstrainer
     */

modules/juce_gui_basics/menus/juce_MenuBarModel.h

@@ -131,7 +131,7 @@ public:
     /** OSX ONLY - Sets the model that is currently being shown as the main
         menu bar at the top of the screen on the Mac.
 
-        You can pass 0 to stop the current model being displayed. Be careful
+        You can pass nullptr to stop the current model being displayed. Be careful
         not to delete a model while it is being used.
 
         An optional extra menu can be specified, containing items to add to the top of