I've used Thunderbird for over twenty (20) years. Due to my work I am always copying images on the screen to the clipboard then pasting them within an new email message. Everything has worked fine for years until I got a new 4K monitor from Dell. The resolution on my previous Thinkpad X1s was 2560x1440 but my current Thinkpad X1 has a resolution of 3840x2160. In addition, the Windows scaling is set to "150% (Recommended)" (for my 4K monitor) whereas my previous Thinkpads with regular monitors was set at 100% scaling. The problem I have is when I copy any section of my screen to the clipboard then paste it into Thunderbird's new email windows the image is about 150% too large. When I do this in any other application there is no resizing. In addition, when I double-click the image in the open new email windows and look at the actual size, it gives the same size as the original image but it's really 50% larger. So, comparing the original image from my Desktop against the image in the new mail window there is a significant size issue. No other application fails to keep the size but it looks like Thunderbird doesn't seem to really know what the size is because their idea of 250x250 image size is really 50% larger than 250x250 in any other software or actually on my desktop. I've attached an image of the two sizes of an image; first the original real size as displayed on the monitor and in any other application I past it to, and the second is the image as it appears pasted into Thunderbird's new email window. I hope this makes sense. I've tried some resize addons and they have been quite unhelpful. So, I suspect Thunderbird isn't handling the Windows scaling. Any thoughts or ideas how to fix this would be appreciated. Thanks,