diff --git a/src/edit.c b/src/edit.c
index f764f9b..b1a13a9 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -3385,8 +3385,8 @@
     if (c != Ctrl_R && vim_is_ctrl_x_key(c))
 	edit_submode_extra = NULL;
 
-    /* Ignore end of Select mode mapping */
-    if (c == K_SELECT)
+    /* Ignore end of Select mode mapping and mouse scroll buttons. */
+    if (c == K_SELECT || c == K_MOUSEDOWN || c == K_MOUSEUP)
 	return retval;
 
     /* Set "compl_get_longest" when finding the first matches. */
@@ -8652,15 +8652,16 @@
     int		up;
 {
     pos_T	tpos;
-# if defined(FEAT_GUI) && defined(FEAT_WINDOWS)
-    win_T	*old_curwin;
+# if defined(FEAT_WINDOWS)
+    win_T	*old_curwin = curwin;
+# endif
+# ifdef FEAT_INS_EXPAND
+    int		did_scroll = FALSE;
 # endif
 
     tpos = curwin->w_cursor;
 
 # if defined(FEAT_GUI) && defined(FEAT_WINDOWS)
-    old_curwin = curwin;
-
     /* Currently the mouse coordinates are only known in the GUI. */
     if (gui.in_use && mouse_row >= 0 && mouse_col >= 0)
     {
@@ -8677,10 +8678,23 @@
 # endif
 	undisplay_dollar();
 
-    if (mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL))
-	scroll_redraw(up, (long)(curwin->w_botline - curwin->w_topline));
-    else
-	scroll_redraw(up, 3L);
+# ifdef FEAT_INS_EXPAND
+    /* Don't scroll the window in which completion is being done. */
+    if (!pum_visible()
+#  if defined(FEAT_WINDOWS)
+	    || curwin != old_curwin
+#  endif
+	    )
+# endif
+    {
+	if (mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL))
+	    scroll_redraw(up, (long)(curwin->w_botline - curwin->w_topline));
+	else
+	    scroll_redraw(up, 3L);
+# ifdef FEAT_INS_EXPAND
+	did_scroll = TRUE;
+# endif
+    }
 
 # if defined(FEAT_GUI) && defined(FEAT_WINDOWS)
     curwin->w_redr_status = TRUE;
@@ -8689,6 +8703,17 @@
     curbuf = curwin->w_buffer;
 # endif
 
+# ifdef FEAT_INS_EXPAND
+    /* The popup menu may overlay the window, need to redraw it.
+     * TODO: Would be more efficient to only redraw the windows that are
+     * overlapped by the popup menu. */
+    if (pum_visible() && did_scroll)
+    {
+	redraw_all_later(NOT_VALID);
+	ins_compl_show_pum();
+    }
+# endif
+
     if (!equalpos(curwin->w_cursor, tpos))
     {
 	start_arrow(&tpos);