I appreciate the offer. Let's see if I can snip the relevant portion of the code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Sdl.LanguagePlatform.Core;
using Sdl.LanguagePlatform.TranslationMemory;
using Sdl.LanguagePlatform.TranslationMemoryApi;
using Sdl.ProjectAutomation.Core;
using Sdl.ProjectAutomation.FileBased;
using Sdl.TranslationStudioAutomation.IntegrationApi;

namespace MySDLPlugin
{
    [TranslationProviderWinFormsUi(Id = "Translation_Provider_Plug_inWinFormsUI",
                                   Name = "Translation_Provider_Plug_inWinFormsUI",
                                   Description = "Translation_Provider_Plug_inWinFormsUI")]
    class MyTranslationProviderWinFormsUI : ITranslationProviderWinFormsUI
    {

        public ITranslationProvider[] Browse(IWin32Window owner, LanguagePair[] languagePairs, ITranslationProviderCredentialStore credentialStore)
        {
                    ProjectsController c = SdlTradosStudio.Application.GetController<ProjectsController>();

            // Method A: use reflection to coerce the "owner" to yield the
            // title of the dialog, and use it to match the name of the project.

            dynamic tlc = owner.GetType().GetProperty("TopLevelControl").GetValue(owner);
            String tlTitle = (String) tlc.GetType().GetProperty("Title").GetValue(tlc);

            FileBasedProject selectedProject = null;
            TranslationProviderConfiguration tpc = null;

            foreach (FileBasedProject pr in c.GetAllProjects())
            {
                string pName = pr.GetProjectInfo().Name;
                if ("Project Settings - " + pName == tlTitle)
                {
                    selectedProject = pr;
                    tpc = selectedProject.GetTranslationProviderConfiguration();
                    break;
                }
            }
            // Method B: use the current or selected projects.
            tpc = c.SelectedProjects.First().GetTranslationProviderConfiguration(); // or
            tpc = c.CurrentProject.GetTranslationProviderConfiguration();
            ...
        }
    }
}

Method A works, but it's horrid and undocumented and I can't believe it's the only way to do it. Method B will reliably get the configuration of the selected project, if there is one (and there isn't always one), or the configuration of the current project, if there is one (and there isn't always one). And if there are both a CurrentProject and a SelectedProjects list of length 1, there's no way to know which one the Browse() method was invoked for, because, as I noted, in the situation where there is both a current/active project and a single selected project in the Projects view that isn't the active one, both CurrentProject and SelectedProjects will be populated and the Project Settings button in the ribbon will edit the CurrentProject if you're in the Files view and the single element in SelectedProjects if you're in the Projects view.

Thanks for your attention.

I've tried but failed.
I do not know how to use Browse instance ('owner' part).

Feels like a waste of time.
Nothings unclear here. But, it is sucks clearly.
Project Settings Configuration Icon do sucks.

If you want to use that pop up, you must select a single "Selected project" strictly at Projects View.
If you have "2 or more Selected  projects" or "0 Selected project" it goes to InActive at Projects View.

You have to know different rule for Files View and Editor View.
In these views, selection does not matter at all.
It show you "Current/Active project" all the time.

What I have tried now:

I have moved my code to a timer_tick event on a non-modal form to give me time to enter various dialogs and browse dialogs.

• Open Project
• Project settings
• Browse for TM / TB in Project Settings
• New Project=>Browse save folder...

The behaviour was consistent throughout: Upon start, the current project was also the selected project.

When selecting a different project (single click) and entering Project settings, although I was in the Settings of said project, the "Current project" was still the bold marked one, the one I was in the settings of was the "Selected" project.

So, if I understand you correctly, you wish to know the origin of the "Browse" dialog? From within Project Settings, this is always the Selected project, no matter whether or not it is also the "Current" one. From some "New Project" dialog, I fail to see the need for this. It might be more fruitful if you described what you actually want to achieve. Here, you may want to try to achieve something you don't really need.