Select element: Only scroll options into view under certain conditions

We should not always scroll into view when the selection box is open, because then any (potentially unrelated) document layout changes will lock the user from scrolling away from the selected option.

Source/Core/Elements/WidgetDropDown.cpp

@@ -153,6 +153,7 @@ void WidgetDropDown::OnRender()
 		// We try to respect user values of 'height', 'min-height', and 'max-height'. However, when we need to shrink the box
 		// we will override the 'height' property.
 
+		const float initial_used_height = selection_element->GetBox().GetSize().y;
 		const Vector2f initial_scroll_offset = {selection_element->GetScrollLeft(), selection_element->GetScrollTop()};
 
 		// Previously set 'height' property from this procedure must be removed for the calculations below to work as intended.
@@ -232,10 +233,13 @@ void WidgetDropDown::OnRender()
 			selection_element->SetOffset(Vector2f(offset_x, offset_y), parent_element);
 		}
 
-		int selection = GetSelection();
+		const float new_used_height = selection_element->GetBox().GetSize().y;
+		const bool should_scroll_into_view =
+			(box_opened_since_last_format || value_changed_since_last_box_format || initial_used_height != new_used_height);
 
-		// Scroll selected element into view, if we have one
-		if (selection != -1)
+		const int selection = GetSelection();
+
+		if (should_scroll_into_view && selection != -1)
 		{
 			ScrollIntoViewOptions scroll_options = {
 				box_opened_since_last_format ? ScrollAlignment::Center : ScrollAlignment::Nearest,
@@ -245,7 +249,9 @@ void WidgetDropDown::OnRender()
 			};
 			GetOption(selection)->ScrollIntoView(scroll_options);
 		}
+
 		box_opened_since_last_format = false;
+		value_changed_since_last_box_format = false;
 		box_layout_dirty = false;
 	}
 
@@ -310,6 +316,7 @@ void WidgetDropDown::OnValueChange(const String& value)
 	parent_element->DispatchEvent(EventId::Change, parameters);
 
 	value_rml_dirty = true;
+	value_changed_since_last_box_format = true;
 }
 
 void WidgetDropDown::SetSelection(Element* select_option, bool force)

Source/Core/Elements/WidgetDropDown.h

@@ -123,6 +123,7 @@ class WidgetDropDown : public EventListener {
 	bool selection_dirty = false;
 	bool value_rml_dirty = false;
 	bool value_layout_dirty = false;
+	bool value_changed_since_last_box_format = false;
 	bool box_layout_dirty = false;
 	bool box_opened_since_last_format = false;
 	bool box_visible = false;