asterix2112: it does not recognize my controller
Controller support has not been implemented yet. That will need to wait until the keyboard UI is finalized, which is dependent on various features either still being added, or subject to change.
For the mouse cursor, a few people ran into that problem with the first D:OS.
Are you shutting down all non-essential programs before starting the game, especially any graphics or chat programs that add an overlay?
With D:OS, EVGA's PrecisionX 16 has been known to cause problems with the mouse cursor; one person could avoid this by adding D:OS to the display server's blacklist, another had to exit out of the program completely.
In the game's Graphics options, try switching to Fake Fullscreen or Windowed mode, and see if that helps. It shouldn't be too hard to do this blindly moving the mouse to highlight buttons, or you can manually edit a configuration file to change the display mode (see below).
Check the mouse configuration in Windows. With D:OS, some of the advanced settings (such as enabling mouse trails) can cause problems with the cursor in-game.
Did you check if there were updated drivers for your mouse? Or did you already install an update and get an extra utility program installed for it, that could be conflicting with the game?
Have you checked for updated drivers in general, and Windows updates?
You can edit the graphicSettings.lsx file (in the '..\Documents\Larian Studios\Divinity Original Sin 2' folder) in Wordpad, or other text editor, to manually change the resolution. Search for 'ScreenHeight':
</node>
<node id="ConfigEntry">
<attribute id="MapKey" value="
ScreenHeight" type="22" />
<attribute id="Type" value="0" type="5" />
<attribute id="Value" value="
1600" type="4" />
</node>
<node id="ConfigEntry">
<attribute id="MapKey" value="
ScreenWidth" type="22" />
<attribute id="Type" value="0" type="5" />
<attribute id="Value" value="
2560" type="4" />
</node>
Search for 'fake' near the start of the file to set the display mode (if both FakeFullscreen and Fullscreen are set to zero, it will be in Window mode... edit the number in value="0" / value="1" in the second line after FakeFullscreenEnabled / Fullscreen).
<node id="ConfigEntry">
<attribute id="MapKey" value="
FakeFullscreenEnabled" type="22" />
<attribute id="Type" value="0" type="5" />
<attribute id="Value"
value="0" type="4" />
</node>
<node id="ConfigEntry">
<attribute id="MapKey" value="FrameCapFPS" type="22" />
<attribute id="Type" value="0" type="5" />
<attribute id="Value" value="60" type="4" />
</node>
<node id="ConfigEntry">
<attribute id="MapKey" value="
Fullscreen" type="22" />
<attribute id="Type" value="0" type="5" />
<attribute id="Value"
value="1" type="4" />
</node>