Unminimizing a shaded window should not unshade this window. I'm pretty sure this was not the case a few versions ago. Note that I'm not sure if this is related to plasma taskbar or KWin, sorry. Step to reproduce: 1. shade a window (so that only the titlebar is still visible) 2. minimize the window in the taskbar 3. click on this window's entry in the taskbar to unminimize this window 4. the window is unminimized but it is not shaded anymore
Task Manager just calls KWindowSystem::unminimizeWindow which just calls xcb_map_window. Bouncing back to kwin.
In that case I'm sorry to say that this cannot be fixed. I hoped for some clever way in taskmanager which would tell more. The problem is that minimize doesn't really exist. It's just an unmap of the window, just as shade. So from window manager perspective there is no way to determine whether the window should be shaded or not. What happens is that the window gets mapped again and then we don't know the users intention. It could be map for unshade or map for unminimize or both.