diff -up vim91/runtime/defaults.vim.copypaste vim91/runtime/defaults.vim
--- vim91/runtime/defaults.vim.copypaste	2025-06-27 06:43:53.000000000 +0200
+++ vim91/runtime/defaults.vim	2025-07-11 09:16:19.013363739 +0200
@@ -70,18 +70,6 @@ sunmap Q
 " Revert with ":iunmap <C-U>".
 inoremap <C-U> <C-G>u<C-U>
 
-" In many terminal emulators the mouse works just fine.  By enabling it you
-" can position the cursor, Visually select and scroll with the mouse.
-" Only xterm can grab the mouse events when using the shift key, for other
-" terminals use ":", select text and press Esc.
-if has('mouse')
-  if &term =~ 'xterm'
-    set mouse=a
-  else
-    set mouse=nvi
-  endif
-endif
-
 " Only do this part when Vim was compiled with the +eval feature.
 if 1
 
diff -up vim91/src/testdir/test_balloon.vim.copypaste vim91/src/testdir/test_balloon.vim
--- vim91/src/testdir/test_balloon.vim.copypaste	2025-07-11 09:16:19.013500976 +0200
+++ vim91/src/testdir/test_balloon.vim	2025-07-11 09:17:20.168187029 +0200
@@ -7,6 +7,7 @@ CheckFeature balloon_eval_term
 source util/screendump.vim
 
 let s:common_script =<< trim [CODE]
+  set mouse=a
   call setline(1, ["one one one", "two tXo two", "three three three"])
   set balloonevalterm balloonexpr=MyBalloonExpr()..s:trailing balloondelay=100
   let s:trailing = '<'  " check that script context is set
diff -up vim91/src/testdir/test_popup.vim.copypaste vim91/src/testdir/test_popup.vim
--- vim91/src/testdir/test_popup.vim.copypaste	2025-07-11 08:58:40.000000000 +0200
+++ vim91/src/testdir/test_popup.vim	2025-07-11 09:16:19.013692144 +0200
@@ -957,6 +957,7 @@ func Test_mouse_popup_position()
   let script =<< trim END
     set mousemodel=popup_setpos
     source $VIMRUNTIME/menu.vim
+    set mouse=a
     call setline(1, join(range(20)))
     func Trigger(col)
       call test_setmouse(1, a:col)
diff -up vim91/src/testdir/test_popupwin.vim.copypaste vim91/src/testdir/test_popupwin.vim
--- vim91/src/testdir/test_popupwin.vim.copypaste	2025-07-11 08:58:40.000000000 +0200
+++ vim91/src/testdir/test_popupwin.vim	2025-07-11 09:16:19.013971633 +0200
@@ -556,6 +556,7 @@ func Test_popup_drag()
   " create a popup that covers the command line
   let lines =<< trim END
 	call setline(1, range(1, 20))
+	set mouse=a
 	split
 	vsplit
 	$wincmd w
@@ -623,6 +624,7 @@ func Test_popup_drag_minwidth()
 
   " create a popup that does not fit
   let lines =<< trim END
+      set mouse=a
       call range(40)
 	      \ ->map({_,i -> string(i)})
 	      \ ->popup_create({
@@ -670,6 +672,7 @@ func Test_popup_drag_termwin()
   let lines =<< trim END
 	set foldmethod=marker
 	call setline(1, range(100))
+	set mouse=a
 	for nr in range(7)
 	  call setline(nr * 12 + 1, "fold {{{")
 	  call setline(nr * 12 + 11, "end }}}")
@@ -722,6 +725,7 @@ func Test_popup_close_with_mouse()
 
   let lines =<< trim END
 	call setline(1, range(1, 20))
+	set mouse=a
 	" With border, can click on X
 	let winid = popup_create('foobar', #{
 	      \ close: 'button',
@@ -1559,6 +1563,7 @@ func Test_popup_beval()
   let lines =<< trim END
 	call setline(1, range(1, 20))
 	call setline(5, 'here is some text to hover over')
+	set mouse=a
 	set balloonevalterm
 	set balloonexpr=BalloonExpr()
 	set balloondelay=100
@@ -2269,6 +2274,7 @@ func Test_popup_scrollbar()
 
   let lines =<< trim END
     call setline(1, range(1, 20))
+    set mouse=a
     hi ScrollThumb ctermbg=blue
     hi ScrollBar ctermbg=red
     let winid = popup_create(['one', 'two', 'three', 'four', 'five',