Improvment frame Handling: In previous version, especially during fast menu operations, from time to time a flicker (in case of cyclic updated views) or corrupted menus appeared. Possible root cause is a interferance in the chain: refresh display (~100ms) => release frame (in parallel to) provide frame (~45ms) => clear frame (~45ms). to improve the behaviour the clear frame loop is not iterated until all bufferes are cleared (before one buffer every~45ms). getFrame() does now iterate through all frame buffers instead reusing the first possible (to avoid ghoust views and to provide more time to housekeeping function for cleanup)