Using Spark 1.0.1 on MacOS X 10.4.3 - closing the buddy list window properly close the window but leaves the app running. However, clicking on the running app in the dock does not show the buddy list again (which is the normal behavior following Apple UI guidelines). In addition, the Spark menu only shows the Spark menu when now windows are open. At the very least a menu should exist to open the buddy list - ideally all the menu options should remain even if no windows are open.
I don’'t think this is a bug in JIRA yet.