Python IDLE. Auto-complete/Show completions not working

The only thing i found so far is that if an editing session of IDLE is connected with python shell (called "interactive mode" in the question, i.e. after an attempt to run the edited script) then "non-interactive" IDLE can autocomplete based on values in interactive window. For example, if I type

a = [];
a.appen

and then hit < Tab > it will do nothing, but if I previously type

a = []

in corresponding python shell, IDLE will autocomplete correctly.

So my only suggestion is import same modules with same names in python shell window in order to make them "visible" for non-interactive IDLE editor.

In my case, I had to open Options menu -> Extensions tab on the editor and look to make sure AutoComplete and other relevant options were enabled. They actually were, but by just clicking on 'Apply' even though I dint have to change anything did the trick for me.

I had the same problem with IDLE, because I want to learn Qt and therefore autocompletion is very useful.

As it says in the settings of IDLE, you can trigger the autocomplete with "Control + Space", e.g. after a "QtGui.". Then a menu opens where you can arrow-scroll through the entries.

Sometimes it has to do with the time you have to wait to get a suggestions.

When you go to options > extensions > general at completions popup wait you can change it to about 500ms. In my case it was 2000ms by default.