Visual Mode: fixed a problem where flood selection did not work correctly when...

Visual Mode: fixed a problem where flood selection did not work correctly when sidedefs were previously marked by other actions

Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySidedef.cs

@@ -609,7 +609,12 @@ namespace CodeImp.DoomBuilder.BuilderModes
 			}
 
 			// [ZZ] use the marking system.
-            if (clearlinedefs) General.Map.Map.ClearMarkedLinedefs(false);
+			if (clearlinedefs)
+			{
+				General.Map.Map.ClearMarkedLinedefs(false);
+				General.Map.Map.ClearMarkedSidedefs(false);
+			}
+
             Sidedef.Line.Marked = true;
 
             // Select