Add "Level Corners" menu option

Marlin/Conditionals_post.h

   #define IS_CARTESIAN !IS_KINEMATIC
 
   /**
+   * No adjustable bed on non-cartesians
+   */
+  #if IS_KINEMATIC
+    #undef LEVEL_BED_CORNERS
+  #endif
+
+  /**
    * SCARA cannot use SLOWDOWN and requires QUICKHOME
    */
   #if IS_SCARA

Marlin/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/AlephObjects/TAZ4/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/AliExpress/CL-260/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Anet/A6/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Anet/A8/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/BQ/Hephestos/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/BQ/Hephestos_2/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/BQ/WITBOX/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Cartesio/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Creality/CR-10/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Felix/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Felix/DUAL/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Folger Tech/i3-2020/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Geeetech/GT2560/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Geeetech/I3_Pro_X-GT2560/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Infitary/i3-M508/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Malyan/M150/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/RepRapWorld/Megatronics/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/RigidBot/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/SCARA/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/TinyBoy2/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Velleman/K8200/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Velleman/K8400/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/Velleman/K8400/Dual-head/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/adafruit/ST7565/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/delta/FLSUN/auto_calibrate/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/delta/FLSUN/kossel_mini/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/delta/generic/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/delta/kossel_mini/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/delta/kossel_pro/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/delta/kossel_xl/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/gCreate/gMax1.5+/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/makibox/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/tvrrug/Round2/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/example_configurations/wt150/Configuration.h

 #if ENABLED(LCD_BED_LEVELING)
   #define MBL_Z_STEP 0.025    // Step size while manually probing Z axis.
   #define LCD_PROBE_Z_RANGE 4 // Z Range centered on Z_MIN_POS for LCD Z adjustment
+  #define LEVEL_BED_CORNERS   // Add an option to move between corners
 #endif
 
 /**

Marlin/language_en.h

 #ifndef MSG_LEVEL_BED
   #define MSG_LEVEL_BED                       _UxGT("Level bed")
 #endif
+#ifndef MSG_LEVEL_CORNERS
+  #define MSG_LEVEL_CORNERS                   _UxGT("Level corners")
+#endif
+#ifndef MSG_NEXT_CORNER
+  #define MSG_NEXT_CORNER                     _UxGT("Next corner")
+#endif
 #ifndef MSG_EDITING_STOPPED
   #define MSG_EDITING_STOPPED                 _UxGT("Mesh Editing Stopped")
 #endif

Marlin/ultralcd.cpp

       lcd_return_to_status();
   }
 
+  void lcd_goto_previous_menu_no_defer() {
+    defer_return_to_status = false;
+    lcd_goto_previous_menu();
+  }
+
 #endif // ULTIPANEL
 
 /**
   #if ENABLED(BABYSTEPPING)
 
     void _lcd_babystep(const AxisEnum axis, const char* msg) {
-      if (lcd_clicked) { defer_return_to_status = false; return lcd_goto_previous_menu(); }
+      if (lcd_clicked) { return lcd_goto_previous_menu_no_defer(); }
       ENCODER_DIRECTION_NORMAL();
       if (encoderPosition) {
         const int16_t babystep_increment = (int32_t)encoderPosition * (BABYSTEP_MULTIPLICATOR);
     #if ENABLED(BABYSTEP_ZPROBE_OFFSET)
 
       void lcd_babystep_zoffset() {
-        if (lcd_clicked) { defer_return_to_status = false; return lcd_goto_previous_menu(); }
+        if (lcd_clicked) { return lcd_goto_previous_menu_no_defer(); }
         defer_return_to_status = true;
         ENCODER_DIRECTION_NORMAL();
         if (encoderPosition) {
     static void lcd_refresh_zprobe_zoffset() { refresh_zprobe_zoffset(); }
   #endif
 
-#if ENABLED(LCD_BED_LEVELING)
+
+  #if ENABLED(LEVEL_BED_CORNERS)
+
+    /**
+     * Level corners, starting in the front-left corner.
+     */
+    static int8_t bed_corner;
+    void _lcd_goto_next_corner() {
+      line_to_z(LOGICAL_Z_POSITION(4.0));
+      switch (bed_corner) {
+        case 0:
+          current_position[X_AXIS] = X_MIN_BED + 10;
+          current_position[Y_AXIS] = Y_MIN_BED + 10;
+          break;
+        case 1:
+          current_position[X_AXIS] = X_MAX_BED - 10;
+          break;
+        case 2:
+          current_position[Y_AXIS] = Y_MAX_BED - 10;
+          break;
+        case 3:
+          current_position[X_AXIS] = X_MIN_BED + 10;
+          break;
+      }
+      planner.buffer_line_kinematic(current_position, MMM_TO_MMS(manual_feedrate_mm_m[X_AXIS]), active_extruder);
+      line_to_z(LOGICAL_Z_POSITION(0.0));
+      if (++bed_corner > 3) bed_corner = 0;
+    }
+
+    void _lcd_corner_submenu() {
+      START_MENU();
+      MENU_ITEM(function, MSG_NEXT_CORNER, _lcd_goto_next_corner);
+      MENU_ITEM(function, MSG_BACK, lcd_goto_previous_menu_no_defer);
+      END_MENU();
+    }
+
+    void _lcd_level_bed_corners() {
+      defer_return_to_status = true;
+      lcd_goto_screen(_lcd_corner_submenu);
+      bed_corner = 0;
+      _lcd_goto_next_corner();
+    }
+
+  #endif // LEVEL_BED_CORNERS
+
+  #if ENABLED(LCD_BED_LEVELING)
 
     /**
      *
      * << Prepare
      *    Auto Home           (if homing needed)
      *    Leveling On/Off     (if data exists, and homed)
-     *    Level Bed
      *    Fade Height: ---    (Req: ENABLE_LEVELING_FADE_HEIGHT)
      *    Mesh Z Offset: ---  (Req: MESH_BED_LEVELING)
      *    Z Probe Offset: --- (Req: HAS_BED_PROBE, Opt: BABYSTEP_ZPROBE_OFFSET)
+     *    Level Bed >
+     *    Level Corners >     (if homed)
      *    Load Settings       (Req: EEPROM_SETTINGS)
      *    Save Settings       (Req: EEPROM_SETTINGS)
      */
 
       MENU_ITEM(submenu, MSG_LEVEL_BED, _lcd_level_bed_continue);
 
+      #if ENABLED(LEVEL_BED_CORNERS)
+        // Move to the next corner for leveling
+        if (axis_homed[X_AXIS] && axis_homed[Y_AXIS] && axis_homed[Z_AXIS])
+          MENU_ITEM(function, MSG_LEVEL_CORNERS, _lcd_level_bed_corners);
+      #endif
+
       #if ENABLED(EEPROM_SETTINGS)
         MENU_ITEM(function, MSG_LOAD_EEPROM, lcd_load_settings);
         MENU_ITEM(function, MSG_STORE_EEPROM, lcd_store_settings);
         if (!g29_in_progress)
       #endif
       MENU_ITEM(submenu, MSG_BED_LEVELING, lcd_bed_leveling);
-    #elif PLANNER_LEVELING
-      MENU_ITEM(gcode, MSG_BED_LEVELING, PSTR("G28\nG29"));
+    #else
+      #if PLANNER_LEVELING
+        MENU_ITEM(gcode, MSG_BED_LEVELING, PSTR("G28\nG29"));
+      #endif
+      #if ENABLED(LEVEL_BED_CORNERS)
+        if (axis_homed[X_AXIS] && axis_homed[Y_AXIS] && axis_homed[Z_AXIS])
+          MENU_ITEM(function, MSG_LEVEL_CORNERS, _lcd_level_bed_corners);
+      #endif
     #endif
 
     #if HAS_M206_COMMAND
       wait_for_user = true;
       while (wait_for_user) idle();
       KEEPALIVE_STATE(IN_HANDLER);
-      defer_return_to_status = false;
-      lcd_goto_previous_menu();
+      lcd_goto_previous_menu_no_defer();
       return current_position[Z_AXIS];
     }