I added an Image control to one of my Shared Content Blocks and selected the option for "Clicking the resized image opens the image in its original size" and when I view the Image in its original size by clicking on it, it displays in a Modal Dialog with no close button for the image which thereby freezes/locks the entire screen. The only way to get out of the screen is to close the entire web page.
Please advise since this is a completely roadblocking bug/defect in Sitefinity v. 5.4!!!