I was used to drap-and-drop the screenshots I wanted to add to my posts directly from the application I use to take them, but it is not anymore possible with the new dialog box.
I can only drag the image to the dialog box once I dropped it on the desktop.
I am using Google Chrome 24.0.1312.57 on Mac OS X 10.8.2.
It doesn't seem a problem with the broswer, since dragging the image from the screenshot application to the address bar of Google Chrome works, and I am able to see the image from the browser.
This is only a problem with Google Chrome. I tried with Safari 6.0.2 running on the same computer, and drag-and-drop works.