Instead of only setting the encode button in set_encodebutton_state(), check source and output files in is_ready_to_encode().
If the source file doesn't exist, display a text saying so under the source file text box. Also mark the source text control invalid and disable the Encode button. Can happen if the user edits the source file name.
If the output file already exists, display a text saying so under the output file text box. A BAlert would be too disruptive, because often you're testing different settings and are deliberately overwriting the output file.
If the output file name is the same as the source, display a text saying so under the output file text box. Also mark the output text control invalid and disable the Encode button.
Instead of only setting the encode button in set_encodebutton_state(), check source and output files in is_ready_to_encode().
If the source file doesn't exist, display a text saying so under the source file text box. Also mark the source text control invalid and disable the Encode button. Can happen if the user edits the source file name.
If the output file already exists, display a text saying so under the output file text box. A BAlert would be too disruptive, because often you're testing different settings and are deliberately overwriting the output file.
If the output file name is the same as the source, display a text saying so under the output file text box. Also mark the output text control invalid and disable the Encode button.
Trim spaces from filenames in _BuildLine().