A new option :opt:tab_bar_min_tabs to control how many tabs must be present before the tab-bar is shown

Fixes #1382

docs/changelog.rst

@@ -18,6 +18,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - A new option :opt:`strip_trailing_spaces` to optionally remove trailing
   spaces from lines when copying to clipboard.
 
+- A new option :opt:`tab_bar_min_tabs` to control how many tabs must be
+  present before the tab-bar is shown (:iss:`1382`)
+
 - Automatically check for new releases and notify when an update is available,
   via the system notification facilities. Can be controlled by
   :opt:`update_check_interval` (:iss:`1342`)

kitty/child-monitor.c

@@ -571,7 +571,7 @@ prepare_to_render_os_window(OSWindow *os_window, double now, unsigned int *activ
 #define TD os_window->tab_bar_render_data
     bool needs_render = os_window->needs_render;
     os_window->needs_render = false;
-    if (TD.screen && os_window->num_tabs > 1) {
+    if (TD.screen && os_window->num_tabs >= OPT(tab_bar_min_tabs)) {
         if (!os_window->tab_bar_data_updated) {
             call_boss(update_tab_bar_data, "K", os_window->id);
             os_window->tab_bar_data_updated = true;
@@ -620,7 +620,7 @@ render_os_window(OSWindow *os_window, double now, unsigned int active_window_id,
     Tab *tab = os_window->tabs + os_window->active_tab;
     BorderRects *br = &tab->border_rects;
     draw_borders(br->vao_idx, br->num_border_rects, br->rect_buf, br->is_dirty, os_window->viewport_width, os_window->viewport_height, active_window_bg, num_visible_windows, os_window);
-    if (TD.screen && os_window->num_tabs > 1) draw_cells(TD.vao_idx, 0, TD.xstart, TD.ystart, TD.dx, TD.dy, TD.screen, os_window, true, false);
+    if (TD.screen && os_window->num_tabs >= OPT(tab_bar_min_tabs)) draw_cells(TD.vao_idx, 0, TD.xstart, TD.ystart, TD.dx, TD.dy, TD.screen, os_window, true, false);
     for (unsigned int i = 0; i < tab->num_windows; i++) {
         Window *w = tab->windows + i;
         if (w->visible && WD.screen) {

kitty/config_data.py

@@ -596,6 +596,10 @@ def tab_font_style(x):
 separated by a configurable separator.
 '''))
 
+o('tab_bar_min_tabs', 2, option_type=lambda x: max(1, positive_int(x)), long_text=_('''
+The minimum number of tabs that must exist before the tab bar is shown
+'''))
+
 
 def tab_fade(x):
     return tuple(map(unit_float, x.split()))

kitty/state.c

@@ -249,7 +249,7 @@ add_borders_rect(id_type os_window_id, id_type tab_id, uint32_t left, uint32_t t
 
 void
 os_window_regions(OSWindow *os_window, Region *central, Region *tab_bar) {
-    if (!global_state.tab_bar_hidden && os_window->num_tabs > 1) {
+    if (!global_state.tab_bar_hidden && os_window->num_tabs >= OPT(tab_bar_min_tabs)) {
         switch(OPT(tab_bar_edge)) {
             case TOP_EDGE:
                 central->left = 0; central->top = os_window->fonts_data->cell_height; central->right = os_window->viewport_width - 1;
@@ -395,6 +395,7 @@ PYWRAP1(set_options) {
     S(macos_window_resizable, PyObject_IsTrue);
     S(macos_hide_from_tasks, PyObject_IsTrue);
     S(macos_thicken_font, PyFloat_AsDouble);
+    S(tab_bar_min_tabs, PyLong_AsUnsignedLong);
 
     GA(tab_bar_style);
     global_state.tab_bar_hidden = PyUnicode_CompareWithASCIIString(ret, "hidden") == 0 ? true: false;

kitty/state.h

@@ -34,6 +34,7 @@ typedef struct {
     float inactive_text_alpha;
     float window_padding_width;
     Edge tab_bar_edge;
+    unsigned long tab_bar_min_tabs;
     bool sync_to_monitor;
     bool close_on_child_death;
     bool window_alert_on_bell;

kitty/tabs.py

@@ -409,17 +409,21 @@ def refresh_sprite_positions(self):
         if not self.tab_bar_hidden:
             self.tab_bar.screen.refresh_sprite_positions()
 
+    @property
+    def tab_bar_should_be_visible(self):
+        return len(self.tabs) >= self.opts.tab_bar_min_tabs
+
     def _add_tab(self, tab):
-        before = len(self.tabs)
+        visible_before = self.tab_bar_should_be_visible
         self.tabs.append(tab)
-        if len(self.tabs) > 1 and before < 2:
+        if not visible_before and self.tab_bar_should_be_visible:
             self.tabbar_visibility_changed()
 
     def _remove_tab(self, tab):
-        before = len(self.tabs)
+        visible_before = self.tab_bar_should_be_visible
         remove_tab(self.os_window_id, tab.id)
         self.tabs.remove(tab)
-        if len(self.tabs) < 2 and before > 1:
+        if visible_before and not self.tab_bar_should_be_visible:
             self.tabbar_visibility_changed()
 
     def _set_active_tab(self, idx):
@@ -433,7 +437,7 @@ def tabbar_visibility_changed(self):
             glfw_post_empty_event()
 
     def mark_tab_bar_dirty(self):
-        if len(self.tabs) > 1 and not self.tab_bar_hidden:
+        if self.tab_bar_should_be_visible and not self.tab_bar_hidden:
             mark_tab_bar_dirty(self.os_window_id)
 
     def update_tab_bar_data(self):
@@ -570,7 +574,7 @@ def activate_tab_at(self, x):
 
     @property
     def blank_rects(self):
-        return self.tab_bar.blank_rects if len(self.tabs) > 1 else ()
+        return self.tab_bar.blank_rects if self.tab_bar_should_be_visible else ()
 
     def destroy(self):
         for t in self: