diff --git a/Docs/src/attributes.but b/Docs/src/attributes.but
index ad7db318..1b8e2fb3 100644
--- a/Docs/src/attributes.but
+++ b/Docs/src/attributes.but
@@ -68,7 +68,7 @@ Replaces dialog (\e{IDD_LICENSE}, \e{IDD_DIR}, \e{IDD_SELCOM}, \e{IDD_INST}, \e{
 
 Specifies the bitmap with the images used for the checks of the component-selection page treeview.
 
-This bitmap should have a size of 96x16 pixels and contain six 16x16 images for the different states (in order: selection mask, not checked, checked, greyed out, unchecked & read-only, checked & read-only). Use magenta as mask color (this area will be transparent).
+This bitmap should have a size of 96x16 pixels, no more than 8bpp (256 colors) and contain six 16x16 images for the different states (in order: selection mask, not checked, checked, greyed out, unchecked & read-only, checked & read-only). Use magenta as mask color (this area will be transparent).
 
 \S2{acompletedtext} CompletedText