Create New Issue page doesn't warn you that you will lose changes when navigating away (BB-1154)

Earlier today I was in the process of creating a new issue for a project hosted on bitbucket (tortoisehg) and wrote a pretty lengthy issue message.

When I was ready to submit it, I was scrolled such that the "Report issue" button wasn't visible, and without realizing what I was actually doing (I don't have a lot of experience with bitbucket), I clicked the bold "Create new" link along the top toolbar ("Create new", "All", "Open", "Mine", "Query") above the grey "Create new issue" panel. This resulted in the loss of my issue text, which was pretty frustrating.

It would be ideal if any action that navigates away from the page would warn that the unsaved data will be lost. If it isn't feasible to perform this globally, I believe that at least the actions on the toolbar should show an alert prior to navigating away.