"Too many open editors" in RT 5.9 for Windows

Hi. This has been discussed before, but without resolution. So I’d humbly ask to look at the issue again.

I can open six raw files simultaneously in RT 5.8 under Windows 10 LTSC.

On the very same system, the successor RT 5.9 balks after only two open files, complaining about Too many open editors. Please close an editor to continue. This severely curtails its usability for me.

Is there any chance to have the developers of the next iteration (RT 6.0) keep an eye on this issue?

From what I can tell, it will take a major reworking of the GUI to get around the Windows linitation. However, there seems to be a way to increase the GDI handle limit if you are willing to edit the registry. It would be simple to add a comfiguration option in RawTherapee that lets the user tell RawTherapee what the new limit is.

You mean, the GDI handle limit is the problem? This is intriguing. Why would that handle limit be smaller in 5.9 than it was in 5.8?

I mean, the Windows version is obviously gelded somehow. Under Linux I never see that aforementioned error message, no matter how many editors I have open. It’s faster too.

But still these limitations wouldn’t preclude 5.9 and its successors from working at least as well under Windows as 5.8 already did, no?

Yes, the problem is the GDI handle limit. Windows has a default limit of 10000. I heard Linux has an equivalent concept as a GDI handle, but the limit is much, much higher. As RawTherapee gains new features, it requires more handles. RawTherapee 5.9 gained the Local Adjustments feature which is huge. Just look at the sheer number of adjusters, buttons, checkboxes, and selectors it has. Each editor tab has its own tool panel which means opening a new tab consumes many handles. You see a significant drop in the number of tabs you can open compared to 5.8 because of this.

Uh-oh. I hoped it would be a (more or less simple) bug in 5.9 that can be fixed with reasonable effort. Oh my. I think I understand the problem much better now.

Thank you for your reply.