Better support for touch interfaces

Hi there! I'm a big fan of Theia and it's potential, especially as a powerful IDE replacement for tablets (such as my iPad Pro). After using Theia on my iPad for a day, I can already see some weak points in terms of usability with a touch interface and mobile accessories.

• Arrows on my iPad Smart Keyboard do not work at all in neither the Terminal nor the Monaco shell. (https://www.grapecity.com/en/forums/wijmo/arrow-keys-dont-work-on-ip)

• Scrolling is a mess due to overscrolling. I had to lightly mod my Theia instance to disable overscrolling.

• Context menus are not dismissible without reloading the page.

• There is no way to resize panels in the IDE from a touch interface.

• The page is very zoomed in because there is no meta-tag controlling the viewport initials size (https://developer.mozilla.org/en-US/docs/Mozilla/Mobile/Viewport_meta_tag)

Theia already serves as an excellent IDE on tablets, and I would love to see it get even better. I would love to contribute to the project and help improve usability on touch interfaces after I get more acquainted with the codebase and guidelines.

Patch List

• Viewport Tag
• Overscroll