File clear.patch of Package rxvt-unicode

--- rxvt-unicode-9.21.orig/src/command.C
+++ rxvt-unicode-9.21/src/command.C
@@ -2913,6 +2913,10 @@ rxvt_term::process_csi_seq ()
       return;
     }
 
+  /* remember the current row on position change, in case there's a clear screen
+   * right after, so that we can add "preserve" the buffer (e.g. on ^L) */
+  static int old_row = -1, was_moved = 0;
+  
   switch (ch)
     {
         /*
@@ -2976,6 +2980,12 @@ rxvt_term::process_csi_seq ()
 
       case CSI_CUP:		/* 8.3.21: (1,1) CURSOR POSITION */
       case CSI_HVP:		/* 8.3.64: (1,1) CHARACTER AND LINE POSITION */
+        /* if moving to row 1, remember current row in case a clear screen comes next */
+        if (nargs == 1 && arg[0] == 1 && current_screen == 0)
+          {
+            was_moved = 1;
+            old_row = screen.cur.row;
+          }
         scr_gotorc (arg[0] - 1, nargs < 2 ? 0 : (arg[1] - 1), 0);
         break;
 
@@ -2987,6 +2997,16 @@ rxvt_term::process_csi_seq ()
         break;
 
       case CSI_ED:		/* 8.3.40: (0) ERASE IN PAGE */
+        if (was_moved)
+          {
+            /* this is most likely a ^L, so we'll go back to where we where before
+             * the position change, add a screen of empty lines, then move back
+             * on top. that way the (scrolling) buffer will be preserved */
+            scr_gotorc (old_row, 0, 0);
+            for (int i = nrow - 1; i > 0; --i)
+                scr_add_lines (L"\r\n", 2);
+            scr_gotorc (0, 0, 0);
+          }
         scr_erase_screen (arg[0]);
         break;
 
@@ -3135,6 +3155,16 @@ rxvt_term::process_csi_seq ()
       default:
         break;
     }
+    if (was_moved > 0)
+      {
+        if (was_moved > 1)
+          {
+            was_moved = 0;
+            old_row = -1;
+          }
+        else
+          ++was_moved;
+      }
 }
 /*}}} */