Scenario: select some UTXOs in the 'Coins' tab. Create a tx and sign it. Close the tx dialog without broadcasting/etc (cancel tx). Signatures would remain for selected UTXOs. Create new tx -> invalid sigs.
Scenario: select some UTXOs in the 'Coins' tab. Create a tx and sign it. Close the tx dialog without broadcasting/etc (cancel tx). Signatures would remain for selected UTXOs. Create new tx -> invalid sigs.