Fix prompt_start_row reset to 0 when opening a file without newline in Nushell

src/painting/painter.rs

@@ -82,7 +82,7 @@
 
     /// Returns the available lines from the prompt down
     pub fn remaining_lines(&self) -> u16 {
         self.screen_height().saturating_sub(self.prompt_start_row)
     }
 
     /// Sets the prompt origin position and screen size for a new line editor
@@ -151,14 +151,14 @@
         // Marking the painter state as larger buffer to avoid animations
         self.large_buffer = required_lines >= screen_height;
 
         // This might not be terribly performant. Testing it out
         let is_reset = || match cursor::position() {
-            Ok(position) => position.1 < self.prompt_start_row,
+            Ok(position) => position.1.abs_diff(self.prompt_start_row) > 1,
             Err(_) => false,
         };
 
         // Moving the start position of the cursor based on the size of the required lines
         if self.large_buffer || is_reset() {
             self.prompt_start_row = 0;
         } else if required_lines >= remaining_lines {
             let extra = required_lines.saturating_sub(remaining_lines);
@@ -419,8 +419,8 @@
         //
         // I assume this is a bug with the position() call but haven't figured that
         // out yet.
         if let Ok(position) = cursor::position() {
             self.prompt_start_row = position.1;
         }
     }