background color for constrained views optional

MVMCoreUI/Atoms/Views/SeparatorView.m

@@ -115,7 +115,6 @@
                 [self setAsLight];
             }
         }
-
     } else {
         self.hidden = YES;
     }
@@ -169,4 +168,8 @@
     return YES;
 }
 
+- (BOOL)copyBackgroundColor {
+    return NO;
+}
+
 @end

MVMCoreUI/Atoms/Views/ViewConstrainingView.m

@@ -326,7 +326,7 @@
     if (self.molecule) {
         [self.molecule setWithJSON:json delegateObject:delegateObject additionalData:additionalData];
     }
-    if (self.constrainedView) {
+    if (self.constrainedView && (![self.constrainedView respondsToSelector:@selector(copyBackgroundColor)] || [self.constrainedView performSelector:@selector(copyBackgroundColor)])) {
         self.backgroundColor = self.constrainedView.backgroundColor;
     }
 }

MVMCoreUI/OtherHandlers/MVMCoreUIViewConstrainingProtocol.h

@@ -21,6 +21,9 @@
 /// Can be used to override any standard constraints that may be added.
 - (BOOL)useStandardConstraints;
 
+/// Determines if the constraining view will copy the background color of the delegate.
+- (BOOL)copyBackgroundColor;
+
 /// Will align if it can.
 - (void)alignHorizontal:(UIStackViewAlignment)alignment;
 - (void)alignVertical:(UIStackViewAlignment)alignment;