Here's what i would like to see

vertical global menu(nextstep) with icons (MS Office)

Pie context menus with labels

a tab bar to deal with icon clutter. if the bar is to go on the top of the screen, the tabs should be under the icons so that you can click on the icons faster by throwing the mouse to the top

Windows taskbar (one click to bring up an app with single window, right click to close, max and minimize

a multiple item clipboard like MS Office but make it part of the OS

a tree widget that let's you see what windows are in each workspace. You should be able to give each workspace a name.
I don't think graphics do a good job with tracking what's in workspaces

minimize and send back icons on the title tab. titles should have icons like Windows. Right click on the tab should bring a context menu and one should have the ability to send or copy any window to any workspace

The title buttons should be more descriptive. x to close, up arrow to zoom, down to minimize, diagonal arrow to send back.

Sliding tabs have unused potential. Perhaps if you send back a window, it would automatically align itself to the other window and slide its tab.

easier color picker. For those who just want the basic colors and don't want to deal with 5 zillion shades of red.

a way to clip part of a webpage and make it into a replicant