Comments on obscure bug removing/deleting object buttons

[MikeBlyth]

I've solved this but it took me several hours to find the problem, so I'm posting here as a reference.

The TTS API documentation says of object.removeButton(n), "Removing an index instantly causes all other higher indexes to shift down 1." That's not quite true. Apparently that shift is done on the next frame. In order to delete all buttons, you need something like

    
for i=0, buttonCount-1 do
    self.targetObject.removeButton(i) -- delete from first to last
end

or

for i = buttonCount-1, 0, -1 do
    self.targetObject.removeButton(i)  -- delete from last to first element
end

and not

    
for i=0, buttonCount-1 do
    self.targetObject.removeButton(0)   -- delete first element n times
end

If the array elements were immediately shifted to fill the removed slot, as they would be with an ordinary Lua array, the latter would work -- deleting the first element n times since the others will be shifted down to fill it. But this does not work.

[LordAshes]

Thanks for the info. It does seem that a lot of TTS stuff updates on the next frame. UI XML changes also update on the next frame.