i´m just starting with all this, so this is probably rather simple to solve...sorry bout that
i got this:
in the lower right view, perspective, the brush wireframe mode wont show stuff anymore (im not familiar with the correct terms yet). the blue grid was also all of a sudden disabled, which was for all modes in that view, but i could restore that. and i could show at least the vertices (in brush wireframe). what also is left is the pivot which is visible if i select something in another view.
maybe mentionable: when i select new "floating Viewport > perspective"everything shows right in the floating window, but when i "tear off floating" the problem persists
i made a screen of all that: http://boing.lima-city.de/Unbenannt-1.jpg