In addition to managing (view, add, assign) the Controls for Events Vulnerabilities for one selected event at a time (by Event), you can also perform the same actions for one selected control at a time (by Control).
From the grid above, you can specify to which events the selected control "Monitoring Gate System Approach" can be applied to mitigate its vulnerabilities given threats/sources.
You can select another control using the "Select a control:" dropdown:
Next to the index column is the "Event Name" column which lists all the events as rows. The succeeding column headings correspond to the Sources Hierarchy of your Riskion model.
The intersecting cells given the events (row) and the covering sources (column) are clickable. Clicking a cell will show a checkmark 
which means that the selected control is a control of the event given the source. Clicking the same cell will uncheck the cell.
From below, the selected control "Monthly Gate System Approach" is a potential control to mitigate the vulnerability of the event "Late Train Running" given the source "Disregarding or Not Following Proper Policies, Processes, or Procedures".
The dark gray cells (disabled) mean that the source is not contributing to the event (event is not vulnerable to the source), thus you will not be able to assign a control for it. This is true for "Late Train Running" given "Lack of Situational Awareness". You can assign to which sources an event is vulnerable on the "Vulnerabilities Grid".
To add a new control to mitigate "Event Consequences", click the 
button.
Here you can specify the Control Name, Cost, and categories. The Control name is required, once you enter the control name the OK button will be enabled.
The added control will be displayed as a new row on the Controls column.
You can add multiple controls at once by pasting them from the clipboard.
You can see the format by hovering on the Paste controls button
Once you are ready, click "Paste controls".
