Move Firefox to a different workspace in Mate desktop

I'm using the Mate desktop, with multiple workspaces. In Mate, I can right-click on the title bar of any window and move the window to another workspace (a context menu with options "Move to Workspace Left", "Move to Workspace Right", "Move to Another Workspace"). However, this doesn't work for Firefox windows. I can't get to this context menu by right-clicking on the top bar of a Firefox window (i.e., the tab bar). It doesn't matter where I click; even if I click on the empty space or click on or near the buttons for minimizing/maximizing/closing the window, I can't open this context menu. It looks like Firefox windows don't have anything that X considers a title bar: if I understand correctly, the top bar on Firefox windows (the "tab bar") doesn't seem to be considered a title bar by X Windows. Is there some mouse combination I can use to move a Firefox window among workspaces, in Mate? (I know that Firefox lets me optionally enable a separate title bar, but I don't want to enable a separate Firefox title bar just for this purpose, as the title bar is just wasted space with no useful information beyond what is already present on the tab bar.)