You can turn the color selector type parameter from "channel" to "key" in order to select a specific color for this mask.
                  
                
                
                Parameters
                
                  - 
                    Color Selector (Color Selector) :   Color selector of the color
                    
                    Parameters common to all Elements
                      - 
                        Loading (Activation State) :         The loading status of the color selector. It can be 
                        
                          loaded
                        , 
                        
                          enabled by not loaded
                         or 
                        
                          unloaded
                        
                      
- 
                        Activation (Activation State) :         The activation status of the color selector. It can be 
                        
                          active
                        , 
                        
                          enabled by not active
                         or 
                        
                          inactive
                        
                      
- 
                        Color Label (sRGB Color) :         Associate a color label to your color selector to make it easily locatable
      
                      
- 
                        Solo (On/off option) :         Activate this to keep only this color selector active and hide all other color selectors in same location
      
                      
- 
                        Editable (Activation State) :         The editabiliy status of the color selector. It can be 
                        
                          locked directly
                        , 
                        
                          locked indirectly
                         or 
                        
                          editable
                        
                      
- 
                        Preset (Element Preset Selector) :         Select a preset to apply on the color selector
                      
- 
                        Status (Object's errors and warnings) :         Warnings and errors associated to this color selector