<p></p>
<p>I have the same issue with not preserving the layer that I pick.  This appears to be due to constructing a URL fragment (<a href="https://www.openstreetmap.org/#map=19/XX/YY" rel="nofollow">https://www.openstreetmap.org/#map=19/XX/YY</a>) for the current editor view that doesn't include the previous layers (<a href="https://www.openstreetmap.org/#map=19/XX/YY&layers=YN" rel="nofollow">https://www.openstreetmap.org/#map=19/XX/YY&layers=YN</a>).  I've never worked on the code for this project, and I don't do much web development, but it seems like there are two ways to fix this:</p>
<ol>
<li>Add the layer info to the generated URL, but I'm not sure where this is stored, or how one would get it</li>
<li>Don't reset the layer when getting a URL fragment without layer parameter, perhaps only doing it when receiving an empty layer parameter (<a href="https://www.openstreetmap.org/#map=19/XX/YY&layers=" rel="nofollow">https://www.openstreetmap.org/#map=19/XX/YY&layers=</a>)</li>
</ol>
<p>I'm not sure which would be a better solution, though</p>

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