diff --git a/kitty/tab_bar.py b/kitty/tab_bar.py
index 8620a4a9d..58080d45d 100644
--- a/kitty/tab_bar.py
+++ b/kitty/tab_bar.py
@@ -151,6 +151,9 @@ def __getattr__(self, name: str) -> str:
 class ExtraData:
     prev_tab: Optional[TabBarData] = None
     next_tab: Optional[TabBarData] = None
+    # true if the draw_tab function is called just for layout. In such cases,
+    # if drawing is expensive the draw_tab function should avoid drawing and
+    # just move the cursor to its final position, as if drawing was performed.
     for_layout: bool = False