Why doesn't running ClearAll["Global`*"] from a custom Palette update local variables colors?

Question

I created a custom palette, with an ActionMenu that executes ClearAll["Global`*"]. It performs the desired action, but the frontend doesn't instantly update the colors from black to blue (standard), as it happens when ClearAll["Global`*"] is executed directly from a notebook cell (it only updates after something else has been executed). Is there a way to initiate a refresh of the frontend display status?

EDIT: Apparently, the same happens when I load a package from a palette (blue doesn’t immediately update to black).

Biysk

I think that the notebook can't check the status of symbols all the time - so it only does it when it knows it's in use, like when you move the cursor. Is this issue a big problem for you? (Aside: all SO posts are automatically signed with your name in the bottom-right corner, so it's preferred if you don't add it to the post.) – Disciple

Not an enormous problem, but I sometime use the ClearAll to find instances of my functions, and so this palette would simplify my actions, but not greatly if I need to do something else to get the different color. reRemoved my signature (I thought I was losing my mind when you first removed because I was certain I had putted it there…) – Biysk

Answer 1

Not exactly elegant, but it works (the main loop has to be called once after ClearAll):

ActionMenu["Clear", 
   {"Clear global variables" :> (ClearAll["Global`*"]; 
         Block[{nb}, nb = CreateDocument[ExpressionCell[42, "Input"], 
                Visible -> False]; SelectionMove[nb, All, Notebook]; 
            SelectionEvaluate[nb]; NotebookDelete[nb];])}]

Of course, one should use the new Mathematica 8 NotebookEvaluate function, but it seems not to work here (i.e.,

ActionMenu["Clear", 
   {"Clear global variables" :> (ClearAll["Global`*"]; 
         Block[{nb}, nb = CreateDocument[ExpressionCell[42, "Input"], 
                Visible -> False]; NotebookEvaluate[nb]; 
     NotebookDelete[nb];])}]

gives an error message

Could not process unknown packet "1".

Lily

Rolf, welcome to StackOverflow! Always good to get another knowledgeable Mathematica user in our community. Hope you'll enjoy it here. As to your answer: I get the same error for the second piece. The first one works, but also generates messages: "ClearAll::clloc: Cannot clear local variable result. >>" – Waters