Hi Jianxia Song ah yes.. I figured so... Yes indeed I had read the docs https://developers.arcgis.com/web-appbuilder/guide/in-panel-and-off-panel-widget.htm
May I please recommend this as a feature enhancement? After all, while the widgets themselves are different in terms of UI rendering (being off-panel, vs in a panel for launchpad) ... I just want to hide their launching button, the icon. I would think simply the ability to put the icon that launches them (instantiate) should not matter whether they are off-panel or in-panel? Once launched, the code and behavior is different. And they are completely fine in how they work and look. It is simply the button that launches them that I want to hide, and I suspect many other people would also like this ability to hide any widget launching button, no matter whether on or off panel. Thank you!