Missing labels

[sebastian-meyer]

• The image manipulation options are missing their labels, so you can't tell which setting is controlled by a specific slider. In addition the box is transparent, which makes it hard to read:
  
• Of all the functions at the top some are missing a label as well: While the zoom and rotation buttons may be recognizable without a label, the cropping feature and the magnifier aren't. For the sake of consistency and accessibility, all functions should have a label.