Q:

vim: mouse click to resize split but not move cursor

How can I configure vim to use the mouse to resize window splits but not
reposition the cursor when I click elsewhere in the buffer ?
:set mouse=n enables window split resizing in Normal Mode
but also moves the cursor when I left-click on some text. But with set mouse= neither work.
It seems the two behaviours are inextricably linked.

A:

It seems the two behaviours are inextricably linked.

You seem to be right. I tried
:nnoremap <LeftMouse> <Nop>

But that suppresses both cursor positioning and window resizing.
I only managed to get close to the behavior you want by storing the current mouse position on the click, and restoring it on the click release. You'll still briefly see the cursor flickering, but at least it maintains its position:
:nnoremap <LeftMouse> m'<LeftMouse>
:nnoremap <LeftRelease> <LeftRelease>g``

