If you haven't upgraded to v3.9 yet, DON'T DO IT! There are major deficiencies with the image editing capabilities of v3.9 versus previous versions. WP 3.9 is a significant downgrade in these capabilities. Why the developers did this, I can't imagine; however, every topic started about this subject gets changed to [resolved] almost immediately when nothing has been resolved. WP 3.9 will significantly increase your web development times and your frustration level! These are the main UNRESOLVED issues as I see them:
1. There doesn’t seem to be a way to get text to appear over an image when the mouse cursor is hovered over it. Adding alt text or a description to the image when it is selected in the “Add Media” dialog box doesn’t result in anything; neither does adding alt text within the “Image Details” dialog box when that is opened within the Visual Editor (by clicking on the pencil icon on a selected image).
2. The size of an image isn’t displayed when resizing it in the visual editor. This used to be present in previous versions and it was a quick aid in adjusting image size.
3. There are no convenient ways of adding padding, margins, or a border to an image except by doing my own coding.
4. Manually adding padding, margins, or a border to an image using the text editor tab is extremely frustrating, because on pages or posts with a lot of images you have to painstakingly search for every image entry, because every time you switch to the text tab the page refocuses at the beginning of the page.
5. Clicking on “Edit Original” in the image editing dialog box only gives you a subset of the features within the true image editing dialog within the Media section.
6. You can no longer increase or decrease the size of an image by a percentage as in the previous version's image editing dialog box.
What can you do in v3.9 you might ask? Only a very small subset of what was possible before and almost nothing of any consequence. No matter how much the developers tout the "new and improved" image editing features of the latest version, the fact is that it is a crippled package with significantly lowered value to users!