It's been happening before and it is still happening in the latest (4.0.1) release of SQL Developer. I have a worksheet opened after opening a sql file. The code itself is some PL/SQL package code which contains errors. I compile the code and get compilation report inside the bottom panel stack. When I double click on one of the errors, a new tab is opened with the same file loaded and I am taken to the line of code where error occures. Database connection gets lost and I have to reconnect before next compilation attend. If I close this worksheet the first one (or all previous) will close too. This is very annoying and it's making me nervous.
I am also experiencingsome performance issues. SQL Developer starts working very slow and it hangs after some time. When I try to close the window I see many background services are closing (SQL developer shows me this), but at a very slow rate.
Is there anythink that could be done or should I switch to TOAD?
I was able to replicate what you are experiencing if I start off in a worksheet and execute the steps. However, if I browse to the actual package and open up the code from there and execute the same steps, it doesn't happen. Suggest that once you create your package (errors or not) use the code view and not the worksheet to edit.
As for the performance issues, without knowing your system configs, can't help on that.