A few suggestions if I may:
- Remove the border around both the title and the field. This is weird and unconventional. There’s a reason no other application does this. Only the input field should have the border.
- Do not show eye/code/pin buttons unless the mouse is over the field or the button is active.
- Please no field icons, this is just more clutter! Or at least make them disableable.
- Do not show overscroll indicators (lines below and above input fields) unless you can scroll. Please do NOT use the CSS trick for this! (I have an add-on that sets the background image for the editor.)
- Make the tag icon not filled—use the one that the Browser shows. In fact, use a single style everywhere.
- Remove the weird empty space below the tag panel.
- Make the distance between buttons constant, make everything aligned, well, more here.