Option to hide the main toolbar

<!-- Thank you for requesting a feature and helping to improve the project --> <!-- Please follow our issue template as much as possible --> <!-- If you can't answer some sections, please delete them --> ### Problem Description For consistency I'd like to enable native title bar, but then the Firefox toolbar takes up vertical space while not being really useful (everything can be accessed through the alt-menu and I rarely need to do that) <!-- Is your feature request related to a problem? --> <!-- Please add a clear description of the problem you are seeking to solve with this feature request --> ### Proposed Solution <!-- Describe the solution you'd like clearly and concisely --> <!-- Also include any alternative solutions or features you've considered --> ### Additional Information <!-- Add any other context about the problem or request here --> <!-- Can you create a PR for this feature? Tell us here. -->