For the classic screens (i.e. non-explorer), no DHTMLX layouts will be involved. Header and footer will look as they do today with center area in use by the currently selected tab.
Header area will be responsive in that when the screen gets to thin for the tabs, they will migrate up to a pulldown menu along with the user area pulldown.
Center area will also be responsive to size where the left navigation area will move to the bottom if needed and the contents of the right area will adjust based on width.
Right cell header area will contain the title and will expand to include the flash message area when a message is present. Currently, the flash messages are not visible if the right cell has been scrolled down.
Right cell footer area will not scroll and will contain either paging controls, form buttons, or not be shown, depending on content.
Some initial requirements/thoughts: