Snipping tool in Windows 7 + 10: Save images with lowercase PNG file extension?

The bytes appear to be hard-coded into the executable:

Update

I was able to edit a copy of SnippingTool.exe to have SnippingTool work as you desire:

Hexadecimal values BEFORE my modification:

Hexadecimal values AFTER my Modification:

My SnippingTool save dialog now:

Note: I would take extreme care when editing binary files using a hex editor in they way that I have. Please make sure you do not modify any system files directly, and be aware that if you choose to modify your own files you do so at your own risk!

Ah, I found one way! Damn easy and did not think of it until now: When entering the filename just add .png in the end. This requires no hack, and is kind of fast (< 1 second).

Update 2018

Since the hex edit suggested did not work out for me, I changed the screenshot software and use now Lightscreen which is tiny and handy, and provides quick shortcuts (Print saves fullscreen immediately to file, CTRL print opens the dialog to capture a screenarea). The tool gives you previews, screenshot history, can even upload to imgur.com directly and returns the URL, and runs portable.

So turning away from Microsoft's snipping tool after being filename bugged so often over the years.

🚀 Update 04/2019

There is a new "Snip & Sketch" feature in Windows 10, with simple but handy features. To open it just hit Win + Shift + S. And it saves with .png.

You can always do this: from the directory where the PNG files are run REN *.PNG *.png from a command prompt.