If this were about the size of the minibuffer/echo-area window then this might be the answer: M-x customize-option resize-mini-windows
.
C-h v resize-mini-windows
tells us:
resize-mini-windows
is a variable defined in C source code
.
Its value is grow-only
Documentation:
How to resize mini-windows (the minibuffer and the echo area).
- A value of
nil
means don't automatically resize mini-windows.
- A value of
t
means resize them to fit the text displayed in them.
- A value of
grow-only
, the default, means let mini-windows grow only;
they return to their normal size when the minibuffer is closed, or the
echo area becomes empty.
You can customize this variable.
This variable was introduced, or its default value was changed, in
version 25.1 of Emacs.
However, it looks like the buffer you're worried about making larger is not the minibuffer/echo-area window. It looks like it's for buffer *Agenda Commands*
, and you seem to have a (somewhat tall) tab bar in the place of its mode-line (?).
I'm assuming you don't see the problem if you start Emacs using emacs -Q
(no init file). In that case, bisect your init file to find the culprit.
If you find out that a part of your init file causes the problem, if that part comes from using some library, you might want to file a bug report with its maintainer. Or you might need to revisit some customization you're doing, if that's causing the problem.