After staging files (all or selected), the Staging files dialogs "Close" button is highlighted, suggesting that it has focus. However, pressing enter does not close the "Staging files" window, but actually activates the "Commit" button of the main window. The "Staging files" windows stays open.

If, before pressing enter, I activate another application and then move back to SourceTree, the enter key works as expected.

Using version 3.3.8 which is not present in the affects versions list