This is about the latest version of TightVNC server for windows x64 running on latest Windows 10 Pro x64 as of 2022-03. This bug is also present in the previous versions.
When windows is set to Dark Mode, then, all of it's mouse cursors are changed to support this mode, especially the text editing vertical line carret cursor which is monochrome black by deafult but it is switched to monochrome white when windows is set to Dark Mode.
Unfortunately, this is not followed/respected by TightVNC server so when working with a remote desktop that has it's windows in dark mode, TightVNC still uses mouse pointers intended for light mode.
This results in black mouse pointer on a black background and makes using the remote desktop cumbersome as it looks like mouse pointer is disappearing or got stuck or disconnected while, actually, it is just invisible as it is hovering above text editing area, which can sometimes be full screen.
Proper solution would be for TightVNC server to detect dark mode on windows and switch to white mouse pointers automatically, but even a simple checkbox in settings: "use dark mode mouse pointers" would do the trick. And from all possible mouse pointers the only one that really matters is that vertical line pointer when editing text.
Thanks.
I've managed to overcome the problem by going to windows control panel and changing the mouse pointer theme to "Windows Black" and now text selection cursor is still black but it has white outline preventing it from ever becoming invisible.
Ah, but that, then, creates another problem, at least on my machine. As soon as I changed my mouse pointer theme, dxgkrnl.sys started acting up and bugging DPC latency on my PC. Spikes up to 4000us and even simple audio tasks stutter. When I switched back the mouse pointer theme to 'none' (which I presume is handled by hardware), the problems are gone. This is on Nvidia GTX1650 with latest drivers.