[Interest] Access forms from an called class?

[Robert Wood]

I have my main window which accesses its form. I have another (non-GUI) 
class I have written that takes BTLE messages in and decodes them. This 
blte_commands class is called from MainWindow and works out what the 
message is and what to do with it.

I would then like to change values back on the mainwindow ui form 
depending on what blte_commands decodes.

I was thinking I could maybe pass a pointer from mainwindow to 
blte_commands and access the form directly from blte_commands, but 
failed with that.

Is what I am trying to do good practice? Is there a way to do this and 
if so, how should I do it please?

Thanks!