You didn't seem to realize there that windowed controls represented a window and painted on a themselves, while graphic controls are child controls painted on their parent window. That is some pretty basic stuff.
Maybe you didn't know, but I stopped using Delphi in 2003 and stopped using Lazarus LCL in early 2006. So that is 9 years ago, so excuse me if I forgot the internals of VCL or LCL. In fpGUI, which I've developed and used since 2006, has a window handle for every widget - they internal design and class hierarchy is very different to VCL or LCL.
You where having troubles with aligning status panels. I thought about answering with a question asking why doesn't you don't just draw the text/images yourself? A trivial solution which would create a better experience all around.
That is the first thing I did. Enabled OwnerDrawn and painted the image inside the 3rd StatusBar panel. The problem was that LCL's Statusbar doesn't adhere to its own rules. Under Windows the statusbar panels accept the width I specified. Under LCL-GTK2 they are ignored. So my image appeared to the left in the StatusBar, and not on the right edge like I intended.
Yet one more bug in LCL.Sure there are inconsistencies in the LCL among platforms,
That's an understatement! No wonder ISV's don't take LCL seriously - it is rife with bugs and inconsistencies. Yes, yes, it is an open source project, volunteers etc. But so is fpGUI, MSEgui, Qt, GTK2/3 etc.
I'm left scratching my head wondering why some people get stumped so easily.
Like I said, I gave up trying to use LCL for cross-platform development many years ago. It's just not good enough for commercial work yet. [my opinion]
I was forced to use LCL recently due to a contracting job. Something that would have taken me 5 minutes in fpGUI, took me half a day in LCL - not because I can't program, but because I had to constantly recheck my LCL workarounds on various platforms to make sure they work everywhere. In fpGUI if a component works on one platform, it works on all of them - 100% of the time. I'm used to that... true cross-platform support.