perf: reduce repaints amount caused by selection (#4889)

Co-authored-by: nerix <nero.9@hotmail.de>
Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/messages/Selection.hpp

@@ -38,7 +38,7 @@ struct SelectionItem {
 
     bool operator!=(const SelectionItem &b) const
     {
-        return this->operator==(b);
+        return !this->operator==(b);
     }
 };
 
@@ -62,6 +62,16 @@ struct Selection {
         }
     }
 
+    bool operator==(const Selection &b) const
+    {
+        return this->start == b.start && this->end == b.end;
+    }
+
+    bool operator!=(const Selection &b) const
+    {
+        return !this->operator==(b);
+    }
+
     bool isEmpty() const
     {
         return this->start == this->end;