Data Manager, instead of having only the option to choose existing tables and views and specifying filters, should also allow to just simply paste a single custom SQL SELECT query and treat the results as a table afterwards.
We have several cases where business users have a "magic" SQL query received from source system owner, and would like to just paste it and use as a source table. The query is so complicated that trying to recreate the result in Qlik by clicking in Data Manager is a fool's errand for someone who would just like to load the data and quickly do some analysis. Sure, you can go to the script editor and add your custom queries there, but script editor is scary (data manager exists for a reason).