Always define MIN_Z_HEIGHT_FOR_HOMING even if 0

Always define MIN_Z_HEIGHT_FOR_HOMING even if 0
Always make a potential rise to `home_offset[Z_AXIS]` possible in G28.
Get rid of some very ugly constructs in MBL (ultralcd.cpp).

Marlin/Conditionals.h

@@ -842,5 +842,20 @@
       #define LCD_FEEDBACK_FREQUENCY_DURATION_MS 2
     #endif
   #endif
+
+  /**
+   * MIN_Z_HEIGHT_FOR_HOMING / Z_RAISE_BETWEEN_PROBINGS
+   */
+   #ifndef MIN_Z_HEIGHT_FOR_HOMING
+     #ifndef Z_RAISE_BETWEEN_PROBINGS
+       #define MIN_Z_HEIGHT_FOR_HOMING 0
+     #else
+       #define MIN_Z_HEIGHT_FOR_HOMING Z_RAISE_BETWEEN_PROBINGS
+     #endif
+   #endif
+   #ifndef Z_RAISE_BETWEEN_PROBINGS
+     #define Z_RAISE_BETWEEN_PROBING MIN_Z_HEIGHT_FOR_HOMING
+   #endif
+
 #endif //CONFIGURATION_LCD
 #endif //CONDITIONALS_H

Marlin/Marlin_main.cpp

@@ -2892,7 +2892,7 @@ inline void gcode_G28() {
         #endif
       }
 
-    #elif defined(MIN_Z_HEIGHT_FOR_HOMING) && MIN_Z_HEIGHT_FOR_HOMING > 0
+    #else
 
       if (home_all_axis || homeX || homeY) {
         // Raise Z before homing any other axes and z is not already high enough (never lower z)
@@ -2913,7 +2913,7 @@ inline void gcode_G28() {
         }
       }
 
-    #endif // MIN_Z_HEIGHT_FOR_HOMING
+    #endif
 
     #if ENABLED(QUICK_HOME)
 

Marlin/ultralcd.cpp

@@ -978,17 +978,13 @@ static void lcd_status_screen() {
     // Note: During Manual Bed Leveling the homed Z position is MESH_HOME_SEARCH_Z
     // Z position will be restored with the final action, a G28
     inline void _mbl_goto_xy(float x, float y) {
-      current_position[Z_AXIS] = MESH_HOME_SEARCH_Z
-        #if MIN_Z_HEIGHT_FOR_HOMING > 0
-          + MIN_Z_HEIGHT_FOR_HOMING
-        #endif
-      ;
+      current_position[Z_AXIS] = MESH_HOME_SEARCH_Z + MIN_Z_HEIGHT_FOR_HOMING;
       line_to_current(Z_AXIS);
       current_position[X_AXIS] = x + home_offset[X_AXIS];
       current_position[Y_AXIS] = y + home_offset[Y_AXIS];
       line_to_current(manual_feedrate[X_AXIS] <= manual_feedrate[Y_AXIS] ? X_AXIS : Y_AXIS);
       #if MIN_Z_HEIGHT_FOR_HOMING > 0
-        current_position[Z_AXIS] = MESH_HOME_SEARCH_Z;
+        current_position[Z_AXIS] = MESH_HOME_SEARCH_Z; // How do condition and action match?
         line_to_current(Z_AXIS);
       #endif
       stepper.synchronize();
@@ -1038,11 +1034,7 @@ static void lcd_status_screen() {
           if (_lcd_level_bed_position == (MESH_NUM_X_POINTS) * (MESH_NUM_Y_POINTS)) {
             lcd_goto_screen(_lcd_level_bed_done, true);
 
-            current_position[Z_AXIS] = MESH_HOME_SEARCH_Z
-              #if MIN_Z_HEIGHT_FOR_HOMING > 0
-                + MIN_Z_HEIGHT_FOR_HOMING
-              #endif
-            ;
+            current_position[Z_AXIS] = MESH_HOME_SEARCH_Z + MIN_Z_HEIGHT_FOR_HOMING;
             line_to_current(Z_AXIS);
             stepper.synchronize();