Although tree.columns[0] correctly returns the leftmost column a undefined property strict JavaScript warning is logged in the JavaScript console.

This happens because nsGenericArraySH::NewResolve does this: if (!JS_GetProperty(cx, obj, "length", &lenval)) { return NS_ERROR_UNEXPECTED; } but the property is called count and not length.

I now have a patch for this, which makes a new attribute, length, which is an alias of count. I am still testing this, but if all goes well, will post the patch shortly.

Comment on attachment 233000 [details] [diff] [review] As before, but bumps IID I can't get to this this week so trying Enn instead.

Comment on attachment 233000 [details] [diff] [review] As before, but bumps IID Looks OK, but get a DOM person to sr it as well.

Comment on attachment 233000 [details] [diff] [review] As before, but bumps IID sr=jst

Checking in layout/xul/base/src/tree/src/nsTreeColumns.cpp; /cvsroot/mozilla/layout/xul/base/src/tree/src/nsTreeColumns.cpp,v <-- nsTreeColumns.cpp new revision: 1.16; previous revision: 1.15 done Checking in layout/xul/base/src/tree/public/nsITreeColumns.idl; /cvsroot/mozilla/layout/xul/base/src/tree/public/nsITreeColumns.idl,v <-- nsITreeColumns.idl new revision: 1.4; previous revision: 1.3 done