How to make frame-title-format persistent?

Question

When I set the title for a frame to current buffers filename via (setq-default frame-title-format '("%b")) the title often falls back to "emacs@" system-name, when the frame is inactive.

I'd expect emacs to keep frame-title, when a frame is inactive, too.

How to keep the title at all times – and only change it, when an other buffer is active? What could cause the unwanted behaviour?

EDIT: Ideal would be, if I could just keep frame-title-format '("%b") – but inactive Frames shouldn't revert to "emacs@" system-name, but keep the filename from active buffer.

Answer 1

A frame title that is set explicitly by modifying the frame parameters will not revert to another name. I do this when creating a frame;e.g., by passing a parameter of (name . "HELLO-WORLD") to the make-frame command. However, it can be done after the frame is already created; e.g., M-x set-frame-name. I do not know how to persistently accomplish this objective by using (setq-default frame-title-format ...).

Here is an example using the make-frame command: https://emacs.stackexchange.com/a/17354/2287