gtk: Make arrow icon in combo button dim

src/gtk/sass/_common-3.20.scss

@@ -1166,6 +1166,15 @@ button.combo:only-child {

                                
                                
                                
                            
                                
                                    
                                        
                                            1166  
                                              &:disabled {
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            1167  
                                                @include entry(disabled);
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            1168  
                                              }
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1169 +
                                        
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1170 +
                                          arrow {
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1171 +
                                            transition: color $duration $ease-out;
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1172 +
                                            color: hint($on-surface);
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1173 +
                                        
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1174 +
                                            &:disabled {
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1175 +
                                              color: disabled-hint($on-surface);
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1176 +
                                            }
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        1177 +
                                          }
                                        
                                        
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            1178  
                                            }
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            1179  
                                            
                                        
                                        
                                            
                                            
                                            
                                            
                                        
                                    
                                
                                
                                
                            
                                
                                    
                                        
                                            1180  
                                            /**