Palette problem

[Richmond]

I have 2 completely independent mainstacks:

1. "Cruddy_Text"; this is a stack containing one selectable textField 
and nothing else.

2. "palette_keyboard"; this contains a single button " 1122.png" 
containing this code:

on mouseUp
    set the useUnicode to true
    put the short name of me into MAGIC
    delete the last char of MAGIC
    delete the last char of MAGIC
    delete the last char of MAGIC
    delete the last char of MAGIC
    -----
       set the unicodeText of the selectedText to numToChar(MAGIC)
    -----
select after the selectedText
end mouseUp

this stack also has this in its stackScript:

on openStack
    palette stack "palette_keyboard"
end openStack

--------------------------------

What I am trying to do is build a floating palette that will let me 
enter Unicode chars
into any selected textField regardless of whether it is in another 
substack of a collection
of stacks, or a free-standing stack.
--------------------------------

What happens is that, having clicked into the textField in stack 
"Cruddy_Text"
I then click on my button in the palettised stack "palette_keyboard" . . .

When I click on the button the field in the other stack is deselected.

And the IDE throws an error:

executing at 10:29:27 PM
Type    Chunk: no target found
Object    1122.png
Line    set the unicodeText of the selectedText to numToChar(1123)
Hint    c

which is a bit worrying.

-----------------------------------

The last time I made a palettised stack was about 3 years ago with LC 
4.5 on Mac (currently working with 6.6 on Linux),
and it changed the thickness of the title bar of the stack, so it was 
obvious it was a palette; this does not seem to
happen just now (although the stack does become a palette).

Richmond.