config, input: allow configuring select-override modifiers

config.c

@@ -1333,6 +1333,10 @@ parse_section_cursor(struct context *ctx)
     return true;
 }
 
+static bool
+parse_modifiers(struct context *ctx, const char *text, size_t len,
+                struct config_key_modifiers *modifiers);
+
 static bool
 parse_section_mouse(struct context *ctx)
 {
@@ -1345,6 +1349,13 @@ parse_section_mouse(struct context *ctx)
     else if (strcmp(key, "alternate-scroll-mode") == 0)
         return value_to_bool(ctx, &conf->mouse.alternate_scroll_mode);
 
+    else if (strcmp(key, "selection-override-modifiers") == 0) {
+        if (!parse_modifiers(ctx, ctx->value, strlen(ctx->value), &conf->mouse.selection_override_modifiers)) {
+            LOG_CONTEXTUAL_ERR("%s: invalid modifiers '%s'", key, ctx->value);
+            return false;
+        }
+    }
+
     else {
         LOG_CONTEXTUAL_ERR("not a valid option: %s", key);
         return false;
@@ -1971,10 +1982,6 @@ value_to_mouse_combos(struct context *ctx, struct key_combo_list *key_combos)
             *key = '\0';
             if (!parse_modifiers(ctx, combo, key - combo, &modifiers))
                 goto err;
-            if (modifiers.shift) {
-                LOG_CONTEXTUAL_ERR("Shift cannot be used in mouse bindings");
-                goto err;
-            }
             key++;  /* Skip past the '+' */
         }
 
@@ -2054,6 +2061,62 @@ err:
     return false;
 }
 
+static bool
+modifiers_equal(const struct config_key_modifiers *mods1,
+                const struct config_key_modifiers *mods2)
+{
+    bool shift = mods1->shift == mods2->shift;
+    bool alt = mods1->alt == mods2->alt;
+    bool ctrl = mods1->ctrl == mods2->ctrl;
+    bool meta = mods1->meta == mods2->meta;
+    return shift && alt && ctrl && meta;
+}
+
+static bool
+modifiers_disjoint(const struct config_key_modifiers *mods1,
+                const struct config_key_modifiers *mods2)
+{
+    bool shift = mods1->shift && mods2->shift;
+    bool alt = mods1->alt && mods2->alt;
+    bool ctrl = mods1->ctrl && mods2->ctrl;
+    bool meta = mods1->meta && mods2->meta;
+    return !(shift || alt || ctrl || meta);
+}
+
+static char *
+modifiers_to_str(const struct config_key_modifiers *mods)
+{
+    char *ret = xasprintf("%s%s%s%s",
+        mods->ctrl ? "Control+" : "",
+        mods->alt ? "Alt+": "",
+        mods->meta ? "Meta+": "",
+        mods->shift ? "Shift+": "");
+    ret[strlen(ret) - 1] = '\0';
+    return ret;
+}
+
+static bool
+selection_override_interferes_with_mouse_binding(struct context *ctx,
+                                                 const struct key_combo_list *key_combos)
+{
+    struct config *conf = ctx->conf;
+
+    const struct config_key_modifiers *override_mods = &conf->mouse.selection_override_modifiers;
+    for (size_t i = 0; i < key_combos->count; i++) {
+        const struct key_combo *combo = &key_combos->combos[i];
+        if (!modifiers_disjoint(&combo->modifiers, override_mods)) {
+            char *modifiers_str = modifiers_to_str(override_mods);
+            LOG_CONTEXTUAL_ERR(
+                "Selection override modifiers (%s) cannot be used in mouse bindings",
+                modifiers_str);
+            free (modifiers_str);
+            return false;
+        }
+    }
+
+    return false;
+}
+
 static bool
 has_mouse_binding_collisions(struct context *ctx,
                              const struct key_combo_list *key_combos)
@@ -2071,14 +2134,10 @@ has_mouse_binding_collisions(struct context *ctx,
             const struct config_key_modifiers *mods1 = &combo1->modifiers;
             const struct config_key_modifiers *mods2 = &combo2->modifiers;
 
-            bool shift = mods1->shift == mods2->shift;
-            bool alt = mods1->alt == mods2->alt;
-            bool ctrl = mods1->ctrl == mods2->ctrl;
-            bool meta = mods1->meta == mods2->meta;
             bool button = combo1->button == combo2->m.button;
             bool count = combo1->count == combo2->m.count;
 
-            if (shift && alt && ctrl && meta && button && count) {
+            if (modifiers_equal(mods1, mods2) && button && count) {
                 bool has_pipe = combo1->pipe.argv.args != NULL;
                 LOG_CONTEXTUAL_ERR("%s already mapped to '%s%s%s%s'",
                                    combo2->text,
@@ -2136,7 +2195,8 @@ parse_section_mouse_bindings(struct context *ctx)
 
         struct key_combo_list key_combos = {0};
         if (!value_to_mouse_combos(ctx, &key_combos) ||
-            has_mouse_binding_collisions(ctx, &key_combos))
+            has_mouse_binding_collisions(ctx, &key_combos) ||
+            selection_override_interferes_with_mouse_binding(ctx, &key_combos))
         {
             free_argv(&pipe_argv);
             free_key_combo_list(&key_combos);
@@ -2780,6 +2840,12 @@ config_load(struct config *conf, const char *conf_path,
         .mouse = {
             .hide_when_typing = false,
             .alternate_scroll_mode = true,
+            .selection_override_modifiers = {
+                .shift = true,
+                .alt = false,
+                .ctrl = false,
+                .meta = false,
+            },
         },
         .csd = {
             .preferred = CONF_CSD_PREFER_SERVER,

config.h

@@ -193,6 +193,7 @@ struct config {
     struct {
         bool hide_when_typing;
         bool alternate_scroll_mode;
+        struct config_key_modifiers selection_override_modifiers;
     } mouse;
 
     struct {

input.c

@@ -701,6 +701,11 @@ keyboard_keymap(void *data, struct wl_keyboard *wl_keyboard,
         seat->kbd.key_arrow_down = xkb_keymap_key_by_name(seat->kbd.xkb_keymap, "DOWN");
     }
 
+    /* Set selection-override modmask from configured mods and seat's mod indices */
+    const struct config_key_modifiers* override_mods =
+        &wayl->conf->mouse.selection_override_modifiers;
+    seat->kbd.selection_override_modmask = conf_modifiers_to_mask(seat, override_mods);
+
     munmap(map_str, size);
     close(fd);
 
@@ -983,7 +988,7 @@ UNITTEST
     xassert(strcmp(info->seq, "\033[27;3;13~") == 0);
 }
 
-static void
+void
 get_current_modifiers(const struct seat *seat,
                       xkb_mod_mask_t *effective,
                       xkb_mod_mask_t *consumed, uint32_t key)
@@ -2372,11 +2377,8 @@ wl_pointer_button(void *data, struct wl_pointer *wl_pointer,
                     get_current_modifiers(seat, &mods, NULL, 0);
                     mods &= seat->kbd.bind_significant;
 
-                    /* Ignore Shift when matching modifiers, since it is
-                     * used to enable selection in mouse grabbing client
-                     * applications */
-                    if (seat->kbd.mod_shift != XKB_MOD_INVALID)
-                        mods &= ~(1 << seat->kbd.mod_shift);
+                    /* Ignore selection override modifiers when matching modifiers */
+                    mods &= ~seat->kbd.selection_override_modmask;
 
                     const struct mouse_binding *match = NULL;
 

input.h

@@ -27,4 +27,9 @@ extern const struct wl_pointer_listener pointer_listener;
 
 void input_repeat(struct seat *seat, uint32_t key);
 
+void get_current_modifiers(const struct seat *seat,
+                           xkb_mod_mask_t *effective,
+                           xkb_mod_mask_t *consumed,
+                           uint32_t key);
+
 const char *xcursor_for_csd_border(struct terminal *term, int x, int y);

terminal.c

@@ -2826,10 +2826,15 @@ term_mouse_grabbed(const struct terminal *term, struct seat *seat)
     /*
      * Mouse is grabbed by us, regardless of whether mouse tracking has been enabled or not.
      */
+
+    xkb_mod_mask_t mods;
+    get_current_modifiers(seat, &mods, NULL, 0);
+
+    const xkb_mod_mask_t override_modmask = seat->kbd.selection_override_modmask;
+    bool override_mods_pressed = (mods & override_modmask) == override_modmask;
+
     return term->mouse_tracking == MOUSE_NONE ||
-        (seat->kbd_focus == term &&
-         seat->kbd.shift &&
-         !seat->kbd.alt && /*!seat->kbd.ctrl &&*/ !seat->kbd.super);
+        (seat->kbd_focus == term && override_mods_pressed);
 }
 
 void

wayland.h

@@ -201,6 +201,8 @@ struct seat {
         xkb_mod_mask_t bind_significant;
         xkb_mod_mask_t kitty_significant;
 
+        xkb_mod_mask_t selection_override_modmask;
+
         xkb_keycode_t key_arrow_up;
         xkb_keycode_t key_arrow_down;