Added more comments to a LookAndFeel assertion that seems to be confusing people

modules/juce_gui_basics/lookandfeel/juce_LookAndFeel.cpp

@@ -50,10 +50,18 @@ LookAndFeel::LookAndFeel()
 
 LookAndFeel::~LookAndFeel()
 {
-    /* This assertion is triggered if you try to delete a LookAndFeel object while it's
-         - still being used as the default LookAndFeel; or
-         - is set as a Component's current lookandfeel; or
-         - pointed to by a WeakReference somewhere else in the code
+    /* This assertion is triggered if you try to delete a LookAndFeel object while something
+       is still using it!
+
+       Reasons may be:
+         - it's still being used as the default LookAndFeel; or
+         - it's set as a Component's current lookandfeel; or
+         - there's a WeakReference to it somewhere else in your code
+
+       Generally the fix for this will be to make sure you call
+       Component::setDefaultLookandFeel (nullptr) on any components that were still using
+       it before you delete it. Or call LookAndFeel::setDefaultLookAndFeel (nullptr) if you
+       had set it up to be the default one.
 
        Deleting a LookAndFeel is unlikely to cause a crash since most things will use a
        safe WeakReference to it, but it could cause some unexpected graphical behaviour,