edit:  

*I don't have source code, and someone says that one would [need to have debug files](https://stackoverflow.com/questions/222456/enable-and-disable-step-into-debugging-on-certain-project-in-a-visual-studio-s) to step in. So, I don't know it's true or not,so I will still ask this question*

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In VS, I am trying to `Attach To Process` to external application to find out, what method (with parameters) is fired on specific button-click.

[Per this solution](https://stackoverflow.com/questions/27775894/getting-the-debugger-to-break-at-the-next-click-event), before I click button, i pause execution and click make "Step In", however, button click is not being caught.

Video: <https://files.fm/u/2wf4gjxb>
(neither checking `Enable just my code` option helps, not unchecking it. Also, it doesn't have any pdb([screenshot](https://i.imgur.com/Wuzg2qG.png)), so i assume it is being considered as external code)

Afaik, the window should be WPF (but someone in comment said, it look slike WinForms). Even WinSpy (or alike) programs are unable to detect buttons when I try to inspect the elements on that window. What should I try?