"Open only one view for multiple files" problem

[xnviewquestioner]

4 years ago another person asked the same question regarding this problem but his solution didn't work for me.
I will use almost the same words he used to formulate my question below:

"In XnView 2.40, in Tools>Options>View I have checked - "Open only one view for multiple files (startup & drag-drop)". When I drag-drop a file into XnView it does correctly open that file in a new tab. But when I double-click a file from Explorer - it always opens that picture in a new window even if an existing window is already open. So if I open x files from Explorer, I get x separate windows of XnView.

When launching a file from Explorer, It should detect if XnView is already open and open that picture in a new tab in the same window."

The solution:
Tools>Options>General - "Only one Instance" checkbox ticked didn't solve the problem!

My operating system is windows 10 x64.....

[xnview]

"Open only one view for multiple files (startup & drag-drop)" is not for that. If you drag&drop muliples files, only one edit view is opened (next/previous used to browse file list).

if you use "Only one Instance", You'll have only ONE XnView, and multiple tabs

[xnviewquestioner]

if you use "Only one Instance", You'll have only ONE XnView, and multiple tabs

I'm sorry for the extreme delay in response, I've totally forgot about opening this topic probably due to circumstances.

However I did select "Only one Instance"!
Look at the screenshot please:



For years now Xnview doesn't open in the same window tabbed.
What's the problem with 'Double Click'......, maybe a bug?