Space key in character replacing mode is processed both by replacement login and gap insertion logic in MSA Editor

Scenario:

1. Open "_common_data/scenarios/msa/ma2_gapped.aln".
2. Select the first character in the first row.
3. Enter the character replacement mode.
4. Press the Space key.
5. Select the last character in the last row.
6. Press the Delete key (to cause the alignment updating and redrawing).
   Expected state: the first character in the first row and the last character in the last row are gaps, the rest characters in the alignment are the same.
   Current state: everything is OK, but a new column of gaps appears.