bold-is-bright.patch

diff --git a/kitty/cell_defines.glsl b/kitty/cell_defines.glsl
index ec6459548..a202b207a 100644
--- a/kitty/cell_defines.glsl
+++ b/kitty/cell_defines.glsl
@@ -3,6 +3,7 @@
 #define FG_OVERRIDE_ALGO {FG_OVERRIDE_ALGO}
 #define TEXT_NEW_GAMMA {TEXT_NEW_GAMMA}
 
+#define BOLD_SHIFT {BOLD_SHIFT}
 #define DECORATION_SHIFT {DECORATION_SHIFT}
 #define REVERSE_SHIFT {REVERSE_SHIFT}
 #define STRIKE_SHIFT {STRIKE_SHIFT}
diff --git a/kitty/cell_vertex.glsl b/kitty/cell_vertex.glsl
index cabed1495..e713d7dfa 100644
--- a/kitty/cell_vertex.glsl
+++ b/kitty/cell_vertex.glsl
@@ -12,6 +12,7 @@ layout(std140) uniform CellRenderData {
     uint columns, lines, sprites_xnum, sprites_ynum, cursor_shape, cell_width, cell_height;
     uint cursor_x1, cursor_x2, cursor_y1, cursor_y2;
     float cursor_opacity, inactive_text_alpha, dim_opacity, blink_opacity;
+    uint bold_is_bright;
 
     // must have unique entries with 0 being default_bg and unset being UINT32_MAX
     uint bg_colors0, bg_colors1, bg_colors2, bg_colors3, bg_colors4, bg_colors5, bg_colors6, bg_colors7;
@@ -96,6 +97,22 @@ uint resolve_color(uint c, uint defval) {
     return is_one * color_table[(c >> 8) & BYTE_MASK] + is_two * (c >> 8) + is_neither_one_nor_two * defval;
 }
 
+uint byte_to_bool(uint n) {
+	uint n1 = (n >> 1) | n;
+	uint n2 = (n1 >> 2) | n1;
+	uint n3 = (n2 >> 4) | n2;
+	return n3 & 1u;
+}
+
+uint brighten_color(uint c, uint is_bold) {
+	uint table_idx = (c >> 8) & 0xFFu;
+	uint is_table_color = c & 1u;
+	uint is_rgb_color = byte_to_bool(c & 0xFEu);
+	uint is_8bit_color = byte_to_bool(table_idx & 0xF8u);
+	uint should_brighten = bold_is_bright * is_bold * (1u >> (is_rgb_color + is_8bit_color)) * is_table_color;
+	return c | (0x800u * should_brighten);
+}
+
 vec3 to_color(uint c, uint defval) {
     return color_to_vec(resolve_color(c, defval));
 }
@@ -305,6 +322,7 @@ void main() {
     // set cell color indices {{{
     uvec2 default_colors = uvec2(default_fg, bg_colors0);
     uint text_attrs = sprite_idx[1];
+    uint is_bold = ((text_attrs >> BOLD_SHIFT) & BIT_MASK);
     uint is_reversed = ((text_attrs >> REVERSE_SHIFT) & BIT_MASK);
     uint is_inverted = is_reversed + inverted;
     int fg_index = fg_index_map[is_inverted];
@@ -315,7 +333,7 @@ void main() {
     bg_as_uint = has_mark * color_table[NUM_COLORS + mark - 1] + (BIT_MASK - has_mark) * bg_as_uint;
     float cell_has_default_bg = 1.f - step(1.f, abs(float(bg_as_uint - bg_colors0))); // 1 if has default bg else 0
     vec3 bg = color_to_vec(bg_as_uint);
-    uint fg_as_uint = resolve_color(colors[fg_index], default_colors[fg_index]);
+    uint fg_as_uint = resolve_color(brighten_color(colors[fg_index], is_bold), default_colors[fg_index]);
     fg_as_uint = has_mark * color_table[NUM_COLORS + MARK_MASK + mark] + (1u - has_mark) * fg_as_uint;
     vec3 foreground = color_to_vec(fg_as_uint);
     CellData cell_data = set_vertex_position(foreground, bg);
diff --git a/kitty/fast_data_types.pyi b/kitty/fast_data_types.pyi
index 70b85c71b..e1edd3e6e 100644
--- a/kitty/fast_data_types.pyi
+++ b/kitty/fast_data_types.pyi
@@ -286,6 +286,7 @@ CELL_BG_PROGRAM: int
 BLIT_PROGRAM: int
 SCREENSHOT_PROGRAM: int
 ROUNDED_RECT_PROGRAM: int
+BOLD: int
 DECORATION: int
 BLINK: int
 DIM: int
diff --git a/kitty/mouse.c b/kitty/mouse.c
index f865343bd..c5d7f055f 100644
--- a/kitty/mouse.c
+++ b/kitty/mouse.c
@@ -953,8 +953,9 @@ handle_tab_bar_mouse(int button, int modifiers, int action) {
         if (w) w->tab_bar_data_updated = false;
         return;
     }
-    // dont report motion events, as they are expensive and useless
-    if (w && (button > -1 || global_state.tab_being_dragged.id)) {
+    // Custom tab bars can use motion events for hover feedback. The stock
+    // Python handler still returns immediately for ordinary non-drag motion.
+    if (w) {
         call_boss(handle_tab_bar_mouse, "Kddiii", w->id, w->mouse_x, w->mouse_y, button, modifiers, action);
     }
 }
@@ -1355,6 +1356,20 @@ mouse_event(const int button, int modifiers, int action) {
     w = r.window; window_idx = r.window_idx;
     set_currently_hovered_window(w && !r.window_border && !r.in_title_bar ? w->id : 0, modifiers, true);
 
+    // Remember whether ordinary pointer motion was last inside this OS
+    // window's tab bar. On the first motion after leaving, send one final
+    // tab-bar motion event with the new (outside) coordinates so a custom
+    // Python tab bar can clear its hover highlight instead of leaving it stuck.
+    static id_type tab_bar_hover_os_window_id = 0;
+    if (button < 0) {
+        if (r.in_tab_bar) {
+            tab_bar_hover_os_window_id = osw->id;
+        } else if (tab_bar_hover_os_window_id == osw->id && !global_state.tab_being_dragged.id) {
+            handle_tab_bar_mouse(button, modifiers, action);
+            tab_bar_hover_os_window_id = 0;
+        }
+    }
+
     if (r.in_tab_bar || global_state.tab_being_dragged.id) {
         mouse_cursor_shape = POINTER_POINTER;
         handle_tab_bar_mouse(button, modifiers, action);
@@ -1497,6 +1512,33 @@ scroll_event(const GLFWScrollEvent *ev) {
         osw->mouse_y = mouse_y * osw->viewport_y_ratio;
     }
     MouseRegion r = mouse_region(false, true);
+
+    // The tab bar has no Screen/Window to receive scroll events, so normally
+    // wheel movement over it is discarded below. Expose vertical wheel
+    // movement to TabManager.handle_tab_bar_mouse() as synthetic button 4/5
+    // presses. A custom tab_bar.py can then use these to cycle tabs.
+    if (r.in_tab_bar) {
+        static double tab_bar_pending_pixels_y = 0.0;
+        // Do not let inertial/momentum scrolling race through many tabs after
+        // the user's fingers have left the touchpad. Physical wheel/touchpad
+        // input arrives with GLFW_NO_MOMENTUM_DATA.
+        if (ev->momentum_type == GLFW_NO_MOMENTUM_DATA && ev->y_offset != 0.0) {
+            int s = scale_scroll(
+                NO_TRACKING,
+                ev->y_offset,
+                ev->offset_type,
+                &tab_bar_pending_pixels_y,
+                osw->fonts_data->fcm.cell_height);
+            if (s) {
+                handle_tab_bar_mouse(
+                    s > 0 ? GLFW_MOUSE_BUTTON_4 : GLFW_MOUSE_BUTTON_5,
+                    ev->keyboard_modifiers,
+                    GLFW_PRESS);
+            }
+        }
+        return;
+    }
+
     Window *w = r.window;
     if (!w && !r.in_tab_bar) {
         // fallback to last active window
diff --git a/kitty/options/definition.py b/kitty/options/definition.py
index 3ef839681..c0c31431a 100644
--- a/kitty/options/definition.py
+++ b/kitty/options/definition.py
@@ -57,6 +57,11 @@
 
 opt('bold_font', 'auto', option_type='parse_font_spec')
 
+opt('bold_is_bright', 'no',
+    option_type='to_bool', ctype='bool',
+    long_text='Display bold text with bright colors'
+    )
+
 opt('italic_font', 'auto', option_type='parse_font_spec')
 
 opt('bold_italic_font', 'auto', option_type='parse_font_spec')
diff --git a/kitty/options/parse.py b/kitty/options/parse.py
index 6f99de673..bef296e0f 100644
--- a/kitty/options/parse.py
+++ b/kitty/options/parse.py
@@ -115,6 +115,9 @@ def bell_path(self, val: str, ans: dict[str, typing.Any]) -> None:
     def bold_font(self, val: str, ans: dict[str, typing.Any]) -> None:
         ans['bold_font'] = parse_font_spec(val)
 
+    def bold_is_bright(self, val: str, ans: dict[str, typing.Any]) -> None:
+        ans['bold_is_bright'] = to_bool(val)
+
     def bold_italic_font(self, val: str, ans: dict[str, typing.Any]) -> None:
         ans['bold_italic_font'] = parse_font_spec(val)
 
diff --git a/kitty/options/to-c-generated.h b/kitty/options/to-c-generated.h
index d209fb78d..3ccf6a9e3 100644
--- a/kitty/options/to-c-generated.h
+++ b/kitty/options/to-c-generated.h
@@ -18,6 +18,19 @@ convert_from_opts_font_size(PyObject *py_opts, Options *opts) {
     Py_DECREF(ret);
 }
 
+static void
+convert_from_python_bold_is_bright(PyObject *val, Options *opts) {
+    opts->bold_is_bright = PyObject_IsTrue(val);
+}
+
+static void
+convert_from_opts_bold_is_bright(PyObject *py_opts, Options *opts) {
+    PyObject *ret = PyObject_GetAttrString(py_opts, "bold_is_bright");
+    if (ret == NULL) return;
+    convert_from_python_bold_is_bright(ret, opts);
+    Py_DECREF(ret);
+}
+
 static void
 convert_from_python_force_ltr(PyObject *val, Options *opts) {
     opts->force_ltr = PyObject_IsTrue(val);
@@ -1530,6 +1543,8 @@ static bool
 convert_opts_from_python_opts(PyObject *py_opts, Options *opts) {
     convert_from_opts_font_size(py_opts, opts);
     if (PyErr_Occurred()) return false;
+    convert_from_opts_bold_is_bright(py_opts, opts);
+    if (PyErr_Occurred()) return false;
     convert_from_opts_force_ltr(py_opts, opts);
     if (PyErr_Occurred()) return false;
     convert_from_opts_disable_ligatures(py_opts, opts);
diff --git a/kitty/options/types.py b/kitty/options/types.py
index cf7009fb1..d6091c9ff 100644
--- a/kitty/options/types.py
+++ b/kitty/options/types.py
@@ -67,6 +67,7 @@
     'bell_on_tab',
     'bell_path',
     'bold_font',
+    'bold_is_bright',
     'bold_italic_font',
     'box_drawing_scale',
     'clear_all_mouse_actions',
@@ -544,6 +545,7 @@ class Options:
     bell_on_tab: str = '🔔 '
     bell_path: str | None = None
     bold_font: FontSpec = FontSpec(family=None, style=None, postscript_name=None, full_name=None, system='auto', axes=(), variable_name=None, features=(), created_from_string='auto')
+    bold_is_bright: bool = False
     bold_italic_font: FontSpec = FontSpec(family=None, style=None, postscript_name=None, full_name=None, system='auto', axes=(), variable_name=None, features=(), created_from_string='auto')
     box_drawing_scale: tuple[float, float, float, float] = (0.001, 1.0, 1.5, 2.0)
     clear_all_mouse_actions: bool = False
diff --git a/kitty/shaders.c b/kitty/shaders.c
index 8d9913642..0473e27c2 100644
--- a/kitty/shaders.c
+++ b/kitty/shaders.c
@@ -471,6 +471,7 @@ cell_update_uniform_block(ssize_t vao_idx, Screen *screen, int uniform_buffer, i
         GLuint columns, lines, sprites_xnum, sprites_ynum, cursor_shape, cell_width, cell_height;
         GLuint cursor_x1, cursor_x2, cursor_y1, cursor_y2;
         GLfloat cursor_opacity, inactive_text_alpha, dim_opacity, blink_opacity;
+        GLuint bold_is_bright;
 
         GLuint bg_colors0, bg_colors1, bg_colors2, bg_colors3, bg_colors4, bg_colors5, bg_colors6, bg_colors7;
         GLfloat bg_opacities0, bg_opacities1, bg_opacities2, bg_opacities3, bg_opacities4, bg_opacities5, bg_opacities6, bg_opacities7;
@@ -486,6 +487,7 @@ cell_update_uniform_block(ssize_t vao_idx, Screen *screen, int uniform_buffer, i
 #define COLOR(name) colorprofile_to_color(cp, cp->overridden.name, cp->configured.name).rgb
     rd->default_fg = COLOR(default_fg);
     rd->highlight_fg = COLOR(highlight_fg); rd->highlight_bg = COLOR(highlight_bg);
+    rd->bold_is_bright = OPT(bold_is_bright) ? 1 : 0;
     rd->extra_cursor_fg = screen->extra_cursors.color.text.val;
     rd->extra_cursor_bg = screen->extra_cursors.color.cursor.val;
     rd->bg_colors0 = COLOR(default_bg);
diff --git a/kitty/shaders.py b/kitty/shaders.py
index 661adc6b1..947d195d5 100644
--- a/kitty/shaders.py
+++ b/kitty/shaders.py
@@ -11,6 +11,7 @@
 from .fast_data_types import (
     BGIMAGE_PROGRAM,
     BLINK,
+    BOLD,
     BLIT_PROGRAM,
     CELL_BG_PROGRAM,
     CELL_FG_PROGRAM,
@@ -178,6 +179,7 @@ def __call__(self, allow_recompile: bool = False) -> None:
                 REVERSE_SHIFT=REVERSE,
                 STRIKE_SHIFT=STRIKETHROUGH,
                 DIM_SHIFT=DIM,
+                BOLD_SHIFT=BOLD,
                 BLINK_SHIFT=BLINK,
                 DECORATION_SHIFT=DECORATION,
                 MARK_SHIFT=MARK,
diff --git a/kitty/state.c b/kitty/state.c
index 56e08965a..a17102fd2 100644
--- a/kitty/state.c
+++ b/kitty/state.c
@@ -1417,7 +1417,7 @@ PYWRAP1(patch_global_colors) {
         else if (PyLong_Check(val)) OPT(name) = PyLong_AsLong(val); \
     } \
 }
-    P(active_border_color); P(inactive_border_color); P(bell_border_color); P(tab_bar_background);
+    P(active_border_color); P(inactive_border_color); P(bell_border_color); P(bold_is_bright); P(tab_bar_background);
     P(tab_bar_margin_color); P(macos_titlebar_color); P(wayland_titlebar_color);
     P(scrollbar_handle_color); P(scrollbar_track_color);
     if (configured) {
diff --git a/kitty/state.h b/kitty/state.h
index 77a15990c..99c73e99f 100644
--- a/kitty/state.h
+++ b/kitty/state.h
@@ -117,6 +117,7 @@ typedef struct Options {
     bool resize_in_steps;
     bool sync_to_monitor;
     bool close_on_child_death;
+    bool bold_is_bright;
     bool window_alert_on_bell;
     bool macos_dock_badge_on_bell;
     bool debug_keyboard;
diff --git a/kitty/window.py b/kitty/window.py
index aa1096d1a..a90bf7331 100644
--- a/kitty/window.py
+++ b/kitty/window.py
@@ -37,6 +37,7 @@
     wakeup_io_loop,
 )
 from .fast_data_types import (
+    BOLD,
     CURSOR_BEAM,
     CURSOR_BLOCK,
     CURSOR_UNDERLINE,