Great observation, this will be filtered by default to tasks in the current project in an upcoming patch. You can set filters by clicking the magnifying glass, but there is no default filter for the current project. Today, you can go an add a filter for the project name (Settings >> Layout >> Workitems >> Default Search Filters), and then enter in the project name to drill into only work items from that project.
I'll also toss in a power-user tip. The fastest way to make dependencies is to select two or more items, and then use the Ctrl+F2 keyboard shortcut (to see a list of all keyboard shortcuts, just press Shift + ? when nothing is selected).