Open Radar

 
Picture the scene. You're writing some awesome code in Xcode. You decide you need to refer to your data model whilst writing, so you double click on the data model to open it in a new window. You hide the toolbar and sidebars in that window, because all you want is to view your data model.

Later, after squashing dozens of bugs and feeling pretty good about yourself, you decide to have a break. You close your Xcode project. Moments after doing so, you realise in horror that you closed the main project window before you closed the window showing your data model. Your heart pulses and your mind races: can you undo what you just did? But no, you can't: it has been done. With a sigh, you close the data model window, knowing that the next time you open your project it will only show you a silly tiny window with no sidebars or toolbars. All because Xcode can't tell the difference between a project window and an auxiliary window.

In the absence of wider changes to the window management model for Xcode, I'd like to suggest a simple fix: if you close a project window that is showing a toolbar, and the only other windows on that project have no toolbar, then the one with the toolbar is what's remembered as the project window state.