patch 8.2.3801: if a terminal shows in two windows, only one is redrawn

Problem:    If a terminal shows in two windows, only one is redrawn.
Solution:   Reset the dirty row range only after redrawing all windows.
            (closes #9341)

src/drawscreen.c

@@ -342,6 +342,13 @@ update_screen(int type_arg)
     update_popups(win_update);
 #endif
 
+#ifdef FEAT_TERMINAL
+    FOR_ALL_WINDOWS(wp)
+	// If this window contains a terminal, after redrawing all windows, the
+	// dirty row range can be reset.
+	term_did_update_window(wp);
+#endif
+
     after_updating_screen(TRUE);
 
     // Clear or redraw the command line.  Done last, because scrolling may

src/proto/terminal.pro

@@ -26,6 +26,7 @@ void term_channel_closed(channel_T *ch);
 void term_check_channel_closed_recently(void);
 int term_do_update_window(win_T *wp);
 void term_update_window(win_T *wp);
+void term_did_update_window(win_T *wp);
 int term_is_finished(buf_T *buf);
 int term_show_buffer(buf_T *buf);
 void term_change_in_curbuf(void);

src/terminal.c

@@ -3850,9 +3850,23 @@ term_update_window(win_T *wp)
 #endif
 				0);
     }
+}
+
+/*
+ * Called after updating all windows: may reset dirty rows.
+ */
+    void
+term_did_update_window(win_T *wp)
+{
+    term_T	*term = wp->w_buffer->b_term;
+
+    if (term != NULL && term->tl_vterm != NULL && !term->tl_normal_mode
+						       && wp->w_redr_type == 0)
+    {
 	term->tl_dirty_row_start = MAX_ROW;
 	term->tl_dirty_row_end = 0;
     }
+}
 
 /*
  * Return TRUE if "wp" is a terminal window where the job has finished.

src/testdir/test_terminal.vim

@@ -1377,6 +1377,32 @@ func Test_terminal_popup_bufload()
   exe 'bwipe! ' .. newbuf
 endfunc
 
+func Test_terminal_popup_two_windows()
+  CheckScreendump
+  CheckUnix
+
+  " use "sh" instead of "&shell" in the hope it will use a short prompt
+  let lines =<< trim END
+      let termbuf = term_start('sh', #{hidden: v:true, term_finish: 'close'})
+      exe 'buffer ' .. termbuf
+
+      let winid = popup_create(termbuf, #{line: 2, minwidth: 30, border: []})
+      sleep 50m
+
+      call term_sendkeys(termbuf, "echo 'test'")
+  END
+  call writefile(lines, 'XpopupScript')
+  let buf = RunVimInTerminal('-S XpopupScript', {})
+
+  " typed text appears both in normal window and in popup
+  call WaitForAssert({-> assert_match("echo 'test'", term_getline(buf, 1))})
+  call WaitForAssert({-> assert_match("echo 'test'", term_getline(buf, 3))})
+
+  call term_sendkeys(buf, "\<CR>exit\<CR>:q\<CR>")
+  call StopVimInTerminal(buf)
+  call delete('XpopupScript')
+endfunc
+
 func Test_terminal_popup_insert_cmd()
   CheckUnix
 
@@ -1402,6 +1428,7 @@ endfunc
 
 func Test_terminal_dumpwrite_composing()
   CheckRunVimInTerminal
+
   let save_enc = &encoding
   set encoding=utf-8
   call assert_equal(1, winnr('$'))

src/version.c

@@ -749,6 +749,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3801,
 /**/
     3800,
 /**/