I did some googling and im not the only one with such issue, I can't play any dosbox game as windowed anymore it shows a black screen unless i alt+enter/fullscreen. I blame microsoft!

Blame them all you want, but it sounds like a misconfiguration that's the result of a PICNIC.

Does the issue occur in DOSBOX Staging?

Ty didnt hear of this one, so it'S like an advanced dosbox? Hehe

More or less I like to put it this way: Imagine a Dosbox dragged kicking and screaming into a modern age.

Underneath the hood, there is a ton of modernizations and code refactorings that make it a lot easier to develop and maintain.

Since one of he latest (Windows 11) updates the classic DosBOX gave me a black command line when using overlay display mode.
Didn't happen with Surface.

Also I didn't have any problems with the Staging variant.

What render mode are you using? Surface, ddraw, opengl?

Default gog setting? When i play a game like darklands from gog library

There's a lot Under the hood to doing configurations. Sometimes you need to get your hands dirty and edit a file or two...

As rtcvb32 said, it's worth learning to play with the settings. GoG doesn't always provide the best settings out of the box - sometimes they don't work well with fullscreen for example. As an example, for games using General Midi music, you can really boost the quality by using some third party software and changing the mixer settings away from the standard midi mapper.

they're leaving us with no choice but to depend on user created ISO images.

Aww ok thanks guys but im just saying i never had this issue before the last few windows 10 updates....And on two difference machines....

I would not be so certain that it's windows related in the first place, I had the same with Windows 11. It might as well be the graphics driver (I'm using Nvidia).

These days we hardly remember, but ~10 years ago after installing a new graphics driver it was always a lottery if video overlay would show at all in Skype or if it was vertically inverted or something. After installing new drivers you always had to adjust your settings.

Try changing the display method in the dosbox configuration file as described above, that should solve the problem.
Really, it's very simple. it's just a text file and all options are displayed inside that file as documentation.
You can't do much wrong, but if you are unsure, make a copy of that file first.

Thanks i will and yes i use nvidia drivers