[Fixed][BUG][EDITOR]Press CTRL+N For New Level, But No Save Level Dialog Appears

[Nessy]

Steps to reproduce:
1. Create a new level or open an existing level, and place at least one terrain/object. Do not save the level yet.
2. Press Ctrl+N to create a new level.

Expected: You should get a dialog asking you if you want to save your level.
Instead: The level disappears and nothing is saved, so all your hard work has the potential to be erased.

[Nepster]

Easily fixed.