Odd... tried it on the latest "normal" release of Lazarus/FPC and got the same result as you. Not sure why it works fine in trunk but not there..... however, using Release FPC/Lazarus, I boiled it down to: it works when the form is included as an "LRS" in the initialization section (which no one should be doing anymore), but not when it is included as an "LFM" (as is the proper way nowadays) in the implementation section. Again, I don't know why this is, exactly. It appears to be an entirely arbitrary limitation, as there is really no reason this shouldn't work all the time (and especially, it's strange that it works with an outdated form file format, but not a current one.)