Hmm, that's right. (Stupid grid controls are poorly designed... they give everyone and everything grief...)

You'll have to help it along. This is what I did. (I used a tStringGrid to test.)

Set...

Ah, yes, that works.

Still, I would repeat myself instead of calling FormCreate again.

procedure TForm1.RedoFunctionButton(Sender: TObject);
begin
memo1.Lines.Text := GetNicAddr;
end;

procedure TForm1.FormCreate( Sender: TObject );
begin
TrayIcon1.PopupMenu := PopupMenu1
end;

This presumes you dropped a popup menu on your form and populated it with the menu designer.

I'll get it to you shortly. I was in the middle of dinking with some stuff in it when I left-off and left it a mess. Once I've cleaned it up better (I should be done by tomorrow) I'll send it to you....

Yes, good job. The only question is: how can you tell the difference between a node that contains a number and a node that contains an operator?

(Have you learned about variant records?)

Also,...

It is hard for a beginner, but not quite "way too hard".

Let me think a bit and post back later. My brain hurts and I'm tired of going around in circles with you.

Some quick things first:
1....

Well, you know that the loop is reading the numbers correctly (because you before tested it by just reading and printing the numbers, and they printed the correct numbers).

But now that you are...

Rather than a bunch of "if foo = x ... " statements, use a "case foo of" statement:

case oper of
'+': begin
...
end;
'-': begin
...
end;
end;

Oy, after all that typing you beat me to the punch with another Q.

Second tutorial: scope.

Just as the functions and procedures above all belonged to tMatrix, so do the variables. Remember how...

Sorry, I should have made myself more clear.

Try this:

procedure TMainForm.RemoveDuplicatesButtonClick(Sender: TObject);
var
i, j, num_removed: integer;
begin
num_removed := 0;...

Alright. Here's a SaveNLines that takes a TListItems.

procedure saveNLines(
filename: string;
var items: tListItems;
startAt: integer;
numLines: integer
);
var
sl: ...

Time enough has passed that I haven't answered here.

As I mentioned already, the reason you see a button on the taskbar is because the application puts it there. Your forms don't. You can see this...