Add scrollback_fill_enlarged_window config option

kitty/config_data.py

@@ -514,6 +514,10 @@ The current implementation stores the data in UTF-8, so approximatively
 10000 lines per megabyte at 100 chars per line, for pure ASCII text, unformatted text.
 A value of zero or less disables this feature. The maximum allowed size is 4GB.'''))
 
+o('scrollback_fill_enlarged_window', False, long_text=_('''
+Fill new space with lines from the scrollback buffer after enlarging a window.
+'''))
+
 o('wheel_scroll_multiplier', 5.0, long_text=_('''
 Modify the amount scrolled by the mouse wheel. Note this is only used for low
 precision scrolling devices, not for high precision scrolling on platforms such

kitty/state.c

@@ -688,6 +688,7 @@ PYWRAP1(set_options) {
     S(dynamic_background_opacity, PyObject_IsTrue);
     S(inactive_text_alpha, PyFloat_AsFloat);
     S(scrollback_pager_history_size, PyLong_AsUnsignedLong);
+    S(scrollback_fill_enlarged_window, PyObject_IsTrue);
     S(cursor_shape, PyLong_AsLong);
     S(cursor_beam_thickness, PyFloat_AsFloat);
     S(cursor_underline_thickness, PyFloat_AsFloat);

kitty/state.h

@@ -32,6 +32,7 @@ typedef struct {
     unsigned int terminal_select_modifiers;
     unsigned int url_style;
     unsigned int scrollback_pager_history_size;
+    bool scrollback_fill_enlarged_window;
     char_type select_by_word_characters[256]; size_t select_by_word_characters_count;
     color_type url_color, background, foreground, active_border_color, inactive_border_color, bell_border_color;
     color_type mark1_foreground, mark1_background, mark2_foreground, mark2_background, mark3_foreground, mark3_background;