patch 8.2.4803: WinScrolled not always triggered when scrolling with mouse

Problem:    WinScrolled not always triggered when scrolling with the mouse.
Solution:   Add calls to may_trigger_winscrolled(). (closes #10246)

src/mouse.c

@@ -1127,6 +1127,7 @@ ins_mousescroll(int dir)
 	}
 #endif
 	did_scroll = TRUE;
+	may_trigger_winscrolled();
     }
 
     curwin->w_redr_status = TRUE;
@@ -2087,6 +2088,7 @@ nv_mousescroll(cmdarg_T *cap)
     if (curwin != old_curwin && curwin->w_p_cul)
 	redraw_for_cursorline(curwin);
 # endif
+    may_trigger_winscrolled();
 
     curwin->w_redr_status = TRUE;
 

src/testdir/test_autocmd.vim

@@ -364,6 +364,37 @@ func Test_WinScrolled()
   call delete('Xtest_winscrolled')
 endfunc
 
+func Test_WinScrolled_mouse()
+  CheckRunVimInTerminal
+
+  let lines =<< trim END
+    set nowrap scrolloff=0
+    set mouse=a term=xterm ttymouse=sgr mousetime=200 clipboard=
+    call setline(1, ['foo']->repeat(32))
+    split
+    let g:scrolled = 0
+    au WinScrolled * let g:scrolled += 1
+  END
+  call writefile(lines, 'Xtest_winscrolled_mouse')
+  let buf = RunVimInTerminal('-S Xtest_winscrolled_mouse', {'rows': 10})
+
+  " With the upper split focused, send a scroll-down event to the unfocused one.
+  call test_setmouse(7, 1)
+  call term_sendkeys(buf, "\<ScrollWheelDown>")
+  call TermWait(buf)
+  call term_sendkeys(buf, ":echo g:scrolled\<CR>")
+  call WaitForAssert({-> assert_match('^1', term_getline(buf, 10))}, 1000)
+
+  " Again, but this time while we're in insert mode.
+  call term_sendkeys(buf, "i\<ScrollWheelDown>\<Esc>")
+  call TermWait(buf)
+  call term_sendkeys(buf, ":echo g:scrolled\<CR>")
+  call WaitForAssert({-> assert_match('^2', term_getline(buf, 10))}, 1000)
+
+  call StopVimInTerminal(buf)
+  call delete('Xtest_winscrolled_mouse')
+endfunc
+
 func Test_WinScrolled_close_curwin()
   CheckRunVimInTerminal
 

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4803,
 /**/
     4802,
 /**/