XnView 1.87: Cannot Minimize

[PJA]

XnView: MP 1.87 - 64-bit
OS: Windows 10 - 64-bit

XnView does not display the buttons: Minimize, Maximize, Close

Effect: XnView always starts Maximized and does not allow me to Minimize; to Close, I can use the ESC key.
This happens for image formats: jpg, png, webp, heic/heif, avif; probably all formats.
I have tried changing several settings that seemed applicable, to no avail.

This bug has been happening for several versions (1.8.6, 1.8.5 ...)
I cannot remember when it started.

I have attached 2 screenshots, one in viewer + one in browser.
I have converted the colors to 256, to minimize (pun intended) file size.

Expected behaviour: Display the buttons Minimize, Maximize, Close

[xnview]

it seems that you have disabled 'View>Title bar'