Hi @cyberfly. Thanks for the report. First, your code is fine: Var mAboutWindow As New winAbout followed by mAboutWindow.Show() is exactly the right way to show a window in Objo. Objo doesn't have Xojo's implicit default instance, hence the extra line, but it has no bearing on the title bar.
What's happening: with TitleBarVisible checked and HasCloseButton unchecked, a running window gets a border but no title bar. The UI framework Objo builds on, and the operating systems underneath it, don't offer a "title bar without a close button" mode - window decorations only come as full, border-only, or none - so turning off HasCloseButton removes the whole native title bar, not just the button. This is documented as best-effort in the HasCloseButton entry on the Window page.
If what you're after is a normal window the user can't close, keep HasCloseButton checked and cancel the close in the window's CancelClosing event instead.
You're right that something on our side is misleading here, though: the designer kept drawing a title bar in this configuration even though the running window won't have one, and that mismatch is exactly what made this confusing. I've logged a fix so the preview shows what the real window will look like: https://feedback.objo.dev/bug/1693
