Hi all.

As many know, running a DOSbox wrapped game from within Steam so you can use the Steam controller and overlay features can be problematic. In order to get those features working with DOSBox on Linux you must use the OpengGL output renderer. The version of DOSbox GOG bundles with older games uses the older (v1) SDL libraries and can have issues with changing resolution on Linux. There is a fork of DOSbox that implements SDL 2 (among other features) at:

[github.com/duganchen/dosbox]

With Dugan's dosbox the games work much better and screen resolution is no longer an issue. However the Steam overlay still works very unreliably due to frame refresh issues created by dos game optimisations. This not only breaks the overlay when activated on some scenes in a game but makes Steam streaming to a unreliable as well. On Windows people have resolved this issue by using builds of Dosbox with DirectX pixel shaders support that force regular frame updates but no such option was available for OpenGL and thus Linux and Mac users were out of luck. So I've dusted of my C++ skills and made a patch that allows setting a minimum frame rate in DOSbox. This feature makes the Steam overlay work perfectly along with much better Steam link streaming. Before I merge my work I was hopping to get some wider testing from the community. I've tested X-Wing, Tie Fighter and Dark Forces so far.

My fork is available at:
[github.com/magicmyth/dosbox/tree/force-frame-update]

I've made a build for testing that should work fine on any Ubuntu 16.04 64bit installation. It might work fine on later Ubuntu releases as well.

[drive.google.com/open?id=0B4dD2fOx1XJyWUhBU2FZRWlVUDA]

To use that first you will need to install libsdl2 and some other bits so enter the following in a terminal:
sudo apt install libsdl2-2.0-0 libsdl2-net-2.0-0 libfluidsynth1

Next go to one of your GOG DOSBox game installation folder. Rename the doxbox folder to something else (dosbox.orig). Then extract the downloaded tar file and move the resulting dosbox folder into the game installtion root folder where you renamed the previous folder.

Next edit the games dosbox_GAMENAME.conf file (e.g. for X-Wing its: dosbox_xwingcd.conf) and make the following changes:
```
[sdl]
...
fullresolution=desktop
output=openglnb
...

[render]
# Force minimum regular frame updates to fix overlay.
forceframeupdate=true
```

Now try the game out from within Steam and let me know how you get on please?

NOTE There is a minor issue where that build will probe for Jack, causing a delay on launch. You can either wait it out (takes only a few seconds) or use the fluidsynth support which bypasses the issue. Looking into getting that fixed in the future.

Thanks to NY00123's and Dugan's GLSL patches you also get the ability to use shaders to enhance the rendering as well (give crt-lottes shader a go on a modern large flatscreen with some strange nostalgia). The shaders and instructions on how to use them can be found over at:
[github.com/duganchen/dosbox_shaders]

Have fun folks

And a thank you to GOG for providing easy access to all these great old dos games :)

bump