Rapidly flickering mouse cursor in Tex Murphy 2

[Arthandas]

The cursor constantly flickers as shown in attached clip.
dosbox 2020-11-30 18-35-00-336.zip

My setup:
Win 10 64-bit, GTX 1060, 16gb ram, i5-7500

Version of dosbox-staging:
0.76.0-alpha-1016-g1702

Configuration parameters:
Default, I tried different output modes (surface mode kinda helps, it still flickers, just less) and number of cycles (the cursor flickers even when setting the cycles to 500). I also tried machine = vesa_nolfb (no effect).

Additional context
The issue persists in other DOSBox versions I tried (official bundled with the game, DOSBox X and Enhanced Community Edition).

[dreamer]

Just today ripsaw merged some change to SVN to address cursor issues… not sure if they address your problem, but just in case: in a few minutes builds will be available here: https://github.com/dosbox-staging/dosbox-staging/actions/runs/392349312

In the meantime I'll try to reproduce the issue on Linux.

[kcgen]

Also confirmed on Linux w/ latest master. The mouse cursor has a slight flicker.
origin/po/test-merge-4393 doesn't change it; still slightly flickering.

[Arthandas]

I don't know if this helps but If you move the cursor down the screen to the action tabs, it completely stops flickering.

[kcgen]

I don't know if this helps but If you move the cursor down the screen to the action tabs, it completely stops flickering.

When over the bottom action panel, the cursor changes to a yellow cursor and indeed stop flickering. But then as soon as you move it up outside the actions, it switches back to a target and resumes flickering. When flickering, the mouse response feels heavy and awkward, compared to the more fluid feeling down on the action bar.

This is a valuable observation @Arthandas, because it shows the issue is an interaction between the DOS game and DOSBox - and unlikely to exist host-side or in SDL.

[kcgen]

YouTube is full of playthroughs, and the flicker is present in every recording that mentions being played with DOSBox.

This recording (https://www.youtube.com/watch?v=BG1mbhc0Cv0) doesn't mention using DOSBox, is distorted to 16:9 which often happens with mid/low cost external HDMI recorders, and the target cursor is rock-steady in the room. Because of the combination of these, I suspect it was recorded on a real DOS machine.

[Arthandas]

Thanks for your time in researching this issue 👍 I hope it's an easy fix. I just can't look at the screen when the cursor flickers like that.

[grapeli]

It's the same everywhere. I checked under qemu, dosemu, dosemu2 and various dosboxes.
The cursor also flashes under dosemu in JSLinux (video).

[kcgen]

@grapeli - thanks for the extensive comparisons!

@Arthandas , if we tinker with various timing intervals in the video code in an attempt to suppress this, there would surely be negative consequences for some unknown number of other games.

My hunch is the fix for this will likely require a change to the game itself. This is something that @ripsaw8080 on the vogons forums is famous for finding and fixing.

[Arthandas]

if we tinker with various timing intervals in the video code in an attempt to suppress this, there would surely be negative consequences for some unknown number of other games.

I hoped this could be fixed by changing some values in the .conf file... Also, I'm surprised no one reported it earlier. Well, there was one topic on GOG but it was ignored. I guess unlike me, people are not bothered by it.

[grapeli]

@Arthandas
I don't think anyone except the authors of the game's code could fix this bug.
During the game, press the F5 key and place the cursor on the panel. The mouse cursor does not blink.

[Arthandas]

I don't think anyone except the authors of the game's code could fix this bug.

Judging by the YT video posted earlier, the issue is not with the game, the cursor doesn't flicker in real DOS.

During the game, press the F5 key and place the cursor on the panel. The mouse cursor does not blink.

Interesting... You don't even need to place the cursor on the panel, it won't flicker as long as it's open, even if you place it outside.

[grapeli]

Judging by the YT video posted earlier, the issue is not with the game, the cursor doesn't flicker in real DOS.

I think I was in a hurry with this assessment.
I ran it under ScummVM and the cursor doesn't blink.

[kcgen]

I ran it under ScummVM and the cursor doesn't blink.

That's expected.. ScummVM re-implements games/engines using modern languages and compilers, from which their executable interfaces directly with the host (as opposed to having anything to do with DOS/Mac/etc..), and then they parse the games' data content.

So this is more evidence that your point, "only the authors of the game's code could fix this bug", is still likely true.

Even if real DOS doesn't have the flicker, the issue of introducing regressions is overwhelming. Also, if other entirely different DOS emulators and even i386 VM (QEMU) exhibit it, this points further at the game itself causing it -- and possibly getting lucky on real hardware with some bug or undocumented/overlooked aspect.

[GranMinigun]

Checked on WinXP machine - flicker is present, but only when cursor doesn't move. Though we replaced CRT monitor recently to TN one. It set to 720x400@70Hz, I think? Maybe the game works somehow differently in real 320x200 w/ double-scan?

[nemo93]

Closing this one off for now. Feel free to reopen if you have new inputs/data.