[Linux] problems with several linux desktop environments

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JohnM
Posts: 379
Joined: Sep 11th, '15, 14:42

Re: [Linux] problems with several linux desktop environments

Post by JohnM » Mar 28th, '18, 16:08

I've tracked down the issue. The problem (at least on Ubuntu 17.10 with the Gnome desktop) is that the SDL2 is reporting multiple key-down events for certain keys like the arrow keys. It also seems to randomly report backspace events, which is what is causing the find box to behave strangely.

This is not a bug in GP itself.

The fact that events work okay on many other Linux desktops makes me suspect that it's either a bug in the Gnome3 desktop's event handling or possibly a bug in SDL2. In fact, the latest version of SDL2, 2.0.8, does not manifest the bug, but that could be because SDL2 added a work-around for an underlying Gnome3 bug. Unfortunately, GP built using that version of SDL2 randomly stops displaying objects in certain projects, a much worse problem! Same with SDL 2.0.7. So, until the SDL display issue is resolved, we need to stick with SDL2 2.0.5, on which GP is stable.

However, I have a partial workaround that involves ignoring the second key-down event when the key-down events are duplicated. That fixes the arrow keys being doubled. It doesn't fix the random behavior of the "find" box, but I've found that the "find" box works okay if you type slowly -- does that work for you?

You might do some detective work with Google to see if you can find any information on Gnome3 bugs that might cause doubled key-down or extra backspace events. It's possible that this is a known problem that will get fixed in a future Gnome release.

MSandro
Posts: 162
Joined: Jul 26th, '17, 21:12

Re: [Linux] problems with several linux desktop environments

Post by MSandro » Mar 28th, '18, 17:18

Nice to know, sure I am glade to be able to help you, so I'll try your suggestion with the search box soon. The newest "stable" release of Gnome is 3.28 atm. Because I've tested GP in Antergos I know even in the newest gnome version this is not fixed currently. But I will search for simular key doubling issues like in GP.

Edit - Search Box:
Even if I type very slowly, the letters disappear.

Edit - SDL:
Maybe this could help: https://stackoverflow.com/questions/221 ... 4#27084554
I don't know much about SDL but I'll try to find some usefull links for you. Until now, I've not found any useful things depending on gnome with doubled key-down or extra backspace events issues. Could it possibly be a problem with your "hard-coded" key input event handler or something simular?

JohnM
Posts: 379
Joined: Sep 11th, '15, 14:42

Re: [Linux] problems with several linux desktop environments

Post by JohnM » Mar 28th, '18, 22:39

MSandro wrote:
Mar 28th, '18, 17:18
Until now, I've not found any useful things depending on gnome with doubled key-down or extra backspace events issues. Could it possibly be a problem with your "hard-coded" key input event handler or something simular?
Thanks for looking.

I can't rule out a bug in the low-level GP code, but it sure looks like it's getting keyboard events from SDL that should never happen (e.g. SDL should not be reporting two key-down events without a keyup event in between). Since this problem doesn't appear in later versions of SDL, it's probably an SDL bug -- perhaps some sort of race-condition or timing dependent bug that doesn't show up in other desktops.

My current plan is to do a GP release soon that includes a work-around for the doubled key-down events at the GP level while continuing to investigate the problem. Perhaps I will find a work around for the backspace key issue in the "find" box, too.

Thanks for helping me track this down.

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