In the July 25 release of Adobe Target, the custom code UX was seriously degraded and should be rolled back to it's previous UX state.
Horizontal Panel view removed
In the previous version, you could display the custom code panel vertically (as we are forced to use now) or horizontally across the bottom of the page.
Custom Code view - Limited editing size
The custom code editing panel is restricted to a very small maximum size within a normal browser window. This severely limits the amount of code you can see while editing, which increases the amount of scrolling you have to do to view the code. The only workarounds I've seen thus far are to expand your browser across two monitors so the % allowed for maximum width is reasonable or to copy the code and do your editing in another application. Neither are feasible or acceptable, considering the previous version did not handicap the editor so poorly.
Closing the Editing panel on save / Interface to open Custom Code
When you save your changes, the editing panel remained open, so you could quickly tweak the code if your reloaded page needed adjustment. This was key when bouncing between pages within an activity to compare code. In the current release, the window closes and you have to click the edit icon. Even a double click of the row would be better. This adds unnecessary disruption while working within Custom Code