**BUG** Concise problem statement: Typing the Backspace key results in the browser going to the previous url. If there is any unsaved work, it is lost even if the browser fwd button is pressed to return to EasyCad. Steps to reproduce bug: 1.Open an easycad schematic and make some changes. Do not save. 2.Press Backspace key in a browser where this key causes the previous url to be opened. 3.Using the browser's fwd button, return to EasyCad. Select the schematic that was opened. Changes are lost. Results: The browser is operated by the backspace key, resulting in lost changes. Expected results: Backspace should be captured if not in an edit box. Alternatively, a javascript dialog should open confirming that changes will be lost with the option to cancel. This behavior is implemented in Wordpress for example when navigating away from a page with unsaved changes. When using one of the program dialogs where it appears that text can be deleted (but in fact cannot) with the backspace key, this bug can result in lost work. Browser:Vivaldi on Kubuntu 16.04