Well… You asked for it…
Basic App Creation
All expression fields should have a clear-expression button so that one doesn’t have to go into Expression Assistant to clear an expression.
Toggling a field from text to expression, or enabling the expression on a column constraint, should automatically open Expression Assistant.
Freeze headers and column names in the column list.
Display all expression fields (including in Expression Assistant) in a fixed-width font.
Don’t resize buttons (e.g., Regenerate Structure) when clicked, so that the user needn’t move the pointer to deliver the confirmation click.
Add expression flask to fields that are expression-capable (e.g., SHOW?, EDITABLE?) in the columns list standard view.
Add on-hover or pop-up tips throughout, especially on the more arcane/obscure labels (e.g., NFC, PII).
Anywhere anything may be rearranged or reordered (e.g., menu views, actions, slice columns), it should be possible using drag-and-drop or with arrow keys.
System-generated ref views and actions should not be sorted separately from user-added ones.
A change to a component (e.g., view, action) that prompts its relocation within the displayed page (e.g., for sorting) should not change its on-screen location. I should not have to go find what I was just configuring after making a change.
Reduce the need for so much scrolling throughout. Less whitespace?
Advanced App Creation
Sort or provide a means to sort tables and slices to suit the preferences of the app creator. With more than just a handful of slices, it becomes a pain to locate the one I want if they aren’t sorted.
Ability to copy column configurations within and between tables.
Ability to add and delete multiple tables without a reload for each.
Ability to regenerate columns of multiple tables at once.
Ability to copy configuration between apps, so that I can easily reproduce features from one app in another without recrafting it all manually.
Ability to disable hints entirely. As an experienced user, I never use them, and the attention-grabbers are an distraction (by design!). I should not be conditioned to ignore attention-grabbers.
Ability to reset User Settings to the default to remove experimental artifacts.
Remove or allow user to hide warnings that have no significance. For instance, gallery views are perfectly usable without images, but a warning is displayed, conditioning me to ignore warnings.
Make the app editor more device-friendly to facilitate app creation on smaller form-factor devices like phones.
Allow comments in expressions.
Improve keyboard navigation; reduce the need for so much pointing and clicking.
Integrate Qrew Tools.
Some method for comparing two versions of the same app, or even different apps; something like diff.
Add regular expressions, please!
Generally, give greater consideration to experienced app creators.
Security
Prevent the app user from accessing views that the app itself doesn’t expressly expose. A user can currently craft a URL to access any view in the app if the user knows the view name or enough about the tables or slices to guess the view name. This allows the user to bypass many of the app creator’s attempts to “secure” an app.
Ability to delete system-generated actions to prompt recreation with default configuration, as can be done with system-generated views.
Ability to delete system-generated views and actions permanently.
Ability to prevent the app from using any auto-generated view (e.g., fasttable).
Ability to prevent any user access to any (e.g., system-generated) view based on a table; ability to restrict user to only views based on slices. Views of tables offer full access to table data and actions, where slices can substantially limit both, vastly improving security. In my opinion, views should not be allowed on tables directly, only on slices.
Stop leaking app config internals in URLs. No table, slice, or column name should be included, nor should any expression. Accepting expressions in URLs allows code injection.