Is RegionAdapter a singleton for different instances of the same control?

[codingdna2]

Hi, not sure is the right place to ask a question, so excuse me in advance if it's not.

Background

I implemented a custom adapter for DXTabControl from DevExpress which supports tabs tear-off in a new window. I followed all your courses on pluralsight and went on and implemented RegionAdapterBase<DXTabControl> in order to add elements to the control itself and a RegionManagerAwareBehavior to set the right IRegionManager inside my ViewModels after creating a Scoped region.

Problem

When I've implemented the RegionAdapterBase, I've followed some examples and placed some class properties until I've realized this variables were overwritten when a second call to Adapt was made (Region and Target).

[brianlagunas]

RegionAdapters are not scoped to a specific region instance. They apply to all regions of that specific control type.

[codingdna2]

Hi Brian, thanks for the fast response. I see a behavior is created for each region, shall I try to move my logic in there? Any suggestion is highly appreciated :)

[brianlagunas]

You will need a combination of an adapter and a behavior. If you get stuck, I do offer consulting services. You can DM me on twitter if you want more information about those services.

[codingdna2]

Hi Brian, that's an option I'm considering... but I've taken the path of pluralsight and I've to try some more.. (surely if I knew before I would have taken a different decision). Hopefully you can reply me one more time before I drop everything and start crying ;)

EDIT:
I now get an error when I tear-off a view containing a sub-region. The RegionManagerRegistrationBehavior detects that targetElement regionManager has changed (ref. TryRegisterRegion, line 110), remove the region from the attachedRegionManager but here things became recursive... Inside RegionManager.Remove(string regionName) it calls UpdateRegions which again call TryRegisterRegion which add the Region to the new RegionManager. Now when stack trace unfolds, the caller is also trying to add the same Region.

[codingdna2]

I've updated the previous comment... Is this a bug?
I've tested changing the second if with an else if and it solve my issue but I'm not sure about other implications.

private void TryRegisterRegion()
{
    DependencyObject targetElement = this.HostControl;
    if (targetElement.CheckAccess())
    {
        IRegionManager regionManager = this.FindRegionManager(targetElement);

        IRegionManager attachedRegionManager = this.GetAttachedRegionManager();

        if (regionManager != attachedRegionManager)
        {
            if (attachedRegionManager != null)
            {
                this.attachedRegionManagerWeakReference = null;
                attachedRegionManager.Regions.Remove(this.Region.Name);    // <= RECURSION HAPPENING HERE
            }
            else if (regionManager != null)       // <= CHANGED THIS
            {
                this.attachedRegionManagerWeakReference = new WeakReference(regionManager);
                regionManager.Regions.Add(this.Region);
            }
        }
    }
}

Edit: of course this can't be the solution but I guess is enough to explain the issue. Next week I'll try to create a minimal repro or a unit test.

[codingdna2]

Opened issue #2471