not movable window

select * from table t
where t.

Window pops up, why it is resizable, but not moveable ?

You mean the completion proposal. This pulldown menu pops up at the location where you type the dot. Why would you expect this pulldown is movable? I'm sure there is no code editor in the world which lets you move such a window.

It isn't moveable because it isn't a window: it's a sort of drop down list. Being able to move it would make as little sense as being able to move the "OK" and "Cancel" buttons.

I was trying to see underlaying 'data' window, as I was writing condition based on data there, and data were like '$%&&@'''', not easy to remember, and no way to see it as I could not move the completion window away.

Hehe... well, just press Esc in that case :)