The next 3 symbols concern the direction to \textit{drag translate} a mask using the \texttt{Alt+LMB} thus making it easy to preserve the current $X$ or $Y$ value when desirable. For some desktop window managers,
such as \textit{UbuntuStudio 16.4} and \textit{Arch}, the Alt key is already in use by the Operating System
so you will have to use Alt+Ctrl instead.
The next 3 symbols concern the direction to \textit{drag translate} a mask using the \texttt{Alt+LMB} thus making it easy to preserve the current $X$ or $Y$ value when desirable. For some desktop window managers,
such as \textit{UbuntuStudio 16.4} and \textit{Arch}, the Alt key is already in use by the Operating System
so you will have to use Alt+Ctrl instead.