MSA Editor 'General' OP tab: wrong spinbox size when it disabled
Scenario:
1. Open "data/samples/CLUSTALW/COI.aln".
2. Open "General" options panel tab.
3. Add "_common_data/fasta/amino_ext.fa" with "Add sequence to this alignment".
Current state: "Threshold" percentage spinbox changed from tow-digit to one-digit