fix padding_lines calculation

Author: enricozb

src/terminal_ui.cc

@@ -589,6 +589,7 @@ void TerminalUI::draw(const DisplayBuffer& display_buffer,
 
     DisplayAtom padding{String{m_padding_char, m_padding_fill ? dim.column : 1}};
 
+    const auto padding_lines = (dim.line + line_offset) - line_index;
     while (line_index < dim.line + line_offset)
         m_window.draw(line_index++, padding, face);
 
@@ -602,7 +603,6 @@ void TerminalUI::draw(const DisplayBuffer& display_buffer,
         for (const LineCount selection_line : selection_lines)
             m_scroll_bar_scratch[(int) scale_to(selection_line, buffer_range, gutter_range)]++;
 
-        const auto padding_lines = (dim.line + line_offset) - line_index;
         const auto visible_lines = range.end - range.begin + padding_lines;
         const auto mark_height = scale_to(visible_lines, buffer_range, gutter_range);