+menu: make menu items dynamic, i.e. context dependent
I create this ticket to support the suggestion of Andre Greeff from issue #15880-54:
What about a split button with a "current page default" and a drop-down menu in one?
Working from the current behaviour in 3.3, the primary idea is to change the current "+" button to a dynamic button, showing "New <type>" based on the currently viewed page. So, while viewing the "Issues" page, this would be "New Issue", "Roadmap" would be "New Version", etc. The right-side of the split button would be a small area with a down arrow, which would open the drop-down menu with all the current options.
This would provide consistent and predictable behaviour across all platforms regardless of input type or screen size, and it would make keyboard navigation easier while tabbing through links on the current page (yes, some people still use that on web pages).
This would be a requirement for feature #23143.