ui: add tab bar, layout editor with drag-to-reposition

- GuiTabBar from raygui v5.0 for Player/Layout tab switching
- Layout tab: 5 draggable element placeholders (Title, Bar, Status,
  Play button, Help) — press+hold+drag to reposition
- Auto-save config file on tab switch from Layout back to Player
- config_save() added to config module
- raygui include path added to Makefile, warnings suppressed via
  #pragma for third-party header

6 files changed, 280 insertions, 2 deletions

diff --git a/Makefile b/Makefile
index be802da..71a058d 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ RAYLIB_SRCS := $(RAYLIB_SRC)/rcore.c $(RAYLIB_SRC)/rshapes.c $(RAYLIB_SRC)/rtext
 RAYLIB_OBJS := $(patsubst $(RAYLIB_SRC)/%.c,$(BUILD_DIR)/raylib/%.o,$(RAYLIB_SRCS))
 
 # Common include paths
-COMMON_INCS := -I$(BUILD_DIR) -I$(RAYLIB_SRC) -I$(RAYLIB_SRC)/external/glfw/include
+COMMON_INCS := -I$(BUILD_DIR) -I$(RAYLIB_SRC) -I$(RAYLIB_SRC)/external/glfw/include -Ideps/raygui/src
 
 # ---------------------------------------------------------------------------
 # Linux native configuration (default target)
diff --git a/src/config.c b/src/config.c
index 1b3ecc2..1399de8 100644
--- a/src/config.c
+++ b/src/config.c
@@ -104,6 +104,10 @@ static int parse_config(const char *path, UILayout *layout)
     }
 
     fclose(fp);
+
+    layout->barX    = (1920.0f - layout->barWidth) / 2.0f;
+    layout->statusY = layout->barY + layout->barHeight + 30.0f;
+
     return loaded;
 }
 
@@ -114,5 +118,29 @@ int config_load(const char *exePath, UILayout *layout)
     char cfgPath[1024];
     build_config_path(exePath, cfgPath, sizeof(cfgPath));
 
-    return parse_config(cfgPath, layout);
+    int loaded = parse_config(cfgPath, layout);
+    layout->barX    = (1920.0f - layout->barWidth) / 2.0f;
+    layout->statusY = layout->barY + layout->barHeight + 30.0f;
+    return loaded;
+}
+
+int config_save(const char *exePath, const UILayout *layout)
+{
+    char cfgPath[1024];
+    build_config_path(exePath, cfgPath, sizeof(cfgPath));
+
+    FILE *fp = fopen(cfgPath, "w");
+    if (!fp) return 0;
+
+    fprintf(fp, "# Study Player layout config\n");
+    fprintf(fp, "title_y=%.2f\n", layout->titleY);
+    fprintf(fp, "bar_y=%.2f\n", layout->barY);
+    fprintf(fp, "bar_height=%.2f\n", layout->barHeight);
+    fprintf(fp, "bar_width=%.2f\n", layout->barWidth);
+    fprintf(fp, "btn_radius=%.2f\n", layout->btnRadius);
+    fprintf(fp, "help_y=%.2f\n", layout->helpY);
+    fprintf(fp, "btn_y=%.2f\n", layout->btnY);
+    fprintf(fp, "btn_center_x=%.2f\n", layout->btnCenterX);
+    fclose(fp);
+    return 1;
 }
diff --git a/src/config.h b/src/config.h
index e2eb65e..ce96a5b 100644
--- a/src/config.h
+++ b/src/config.h
@@ -14,3 +14,4 @@ typedef struct {
 } UILayout;
 
 int config_load(const char *exePath, UILayout *layout);
+int config_save(const char *exePath, const UILayout *layout);
diff --git a/src/layout_editor.c b/src/layout_editor.c
new file mode 100644
index 0000000..a728548
--- /dev/null
+++ b/src/layout_editor.c
@@ -0,0 +1,206 @@
+#include "layout_editor.h"
+#include "raylib.h"
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#define RAYGUI_IMPLEMENTATION
+#include "raygui.h"
+#pragma GCC diagnostic pop
+
+#define TITLE_W     400.0f
+#define TITLE_H     70.0f
+#define TIME_W      80.0f
+#define PCT_W       60.0f
+#define PCT_H       30.0f
+#define STATUS_W    120.0f
+#define STATUS_H    40.0f
+#define HELP_W      600.0f
+#define HELP_H      30.0f
+
+static int   dragIndex  = -1;
+static float dragOffsetX = 0.0f;
+static float dragOffsetY = 0.0f;
+
+void layout_editor_init(void)
+{
+    GuiLoadStyleDefault();
+}
+
+static Color fillColor     = {  60,  60,  80, 100 };
+static Color borderColor   = { 180, 180, 200, 200 };
+static Color highlightColor = { 233,  69,  96, 150 };
+static Color labelColor    = { 234, 234, 234, 255 };
+static const int labelFontSize = 20;
+
+static void draw_label(const char *text, Rectangle r, Color fill, Color border)
+{
+    DrawRectangleRec(r, fill);
+    DrawRectangleLinesEx(r, 2.0f, border);
+    int textY = (int)(r.y + r.height / 2.0f - (float)labelFontSize / 2.0f);
+    DrawText(text, (int)r.x + 10, textY, labelFontSize, labelColor);
+}
+
+void layout_editor_draw(const char *exePath, UILayout *layout)
+{
+    (void)exePath;
+
+    int   screenW = GetScreenWidth();
+    Vector2 mouse  = GetMousePosition();
+
+    /* --- Hit detection on press --- */
+    if (IsMouseButtonPressed(MOUSE_BUTTON_LEFT)) {
+        dragIndex = -1;
+
+        /* Check element 4 first (Help), then 3, 2, 1, 0.
+           Later checks overwrite earlier ones if they overlap —
+           priority goes to elements drawn last / on top. */
+
+        /* 4: Help */
+        {
+            Rectangle r = { 40.0f, layout->helpY, HELP_W, HELP_H };
+            if (CheckCollisionPointRec(mouse, r)) {
+                dragIndex  = 4;
+                dragOffsetY = mouse.y - layout->helpY;
+            }
+        }
+
+        /* 3: Play button (circle) */
+        {
+            float dx = mouse.x - layout->btnCenterX;
+            float dy = mouse.y - layout->btnY;
+            if (dx * dx + dy * dy <= layout->btnRadius * layout->btnRadius) {
+                dragIndex  = 3;
+                dragOffsetX = mouse.x - layout->btnCenterX;
+                dragOffsetY = mouse.y - layout->btnY;
+            }
+        }
+
+        /* 2: Status */
+        {
+            Rectangle r = { (float)screenW / 2.0f - STATUS_W / 2.0f,
+                           layout->statusY, STATUS_W, STATUS_H };
+            if (CheckCollisionPointRec(mouse, r)) {
+                dragIndex  = 2;
+                dragOffsetY = mouse.y - layout->statusY;
+            }
+        }
+
+        /* 1: Bar group (bar + time labels + percentage) */
+        {
+            float gx = layout->barX - 90.0f;
+            float gw = layout->barWidth + 10.0f + 80.0f + 90.0f;
+            float gy = layout->barY - 40.0f;
+            float gh = layout->barHeight + 40.0f;
+            Rectangle group = { gx, gy, gw, gh };
+            if (CheckCollisionPointRec(mouse, group)) {
+                dragIndex  = 1;
+                dragOffsetX = mouse.x - layout->barX;
+                dragOffsetY = mouse.y - layout->barY;
+            }
+        }
+
+        /* 0: Title */
+        {
+            Rectangle r = { (float)screenW / 2.0f - TITLE_W / 2.0f,
+                           layout->titleY, TITLE_W, TITLE_H };
+            if (CheckCollisionPointRec(mouse, r)) {
+                dragIndex  = 0;
+                dragOffsetY = mouse.y - layout->titleY;
+            }
+        }
+    }
+
+    /* --- Drag update --- */
+    if (IsMouseButtonDown(MOUSE_BUTTON_LEFT) && dragIndex >= 0) {
+        switch (dragIndex) {
+        case 0: /* Title */
+            layout->titleY = mouse.y - dragOffsetY;
+            break;
+        case 1: /* Bar group */
+            layout->barX = mouse.x - dragOffsetX;
+            layout->barY = mouse.y - dragOffsetY;
+            break;
+        case 2: /* Status */
+            layout->statusY = mouse.y - dragOffsetY;
+            break;
+        case 3: /* Play button */
+            layout->btnCenterX = mouse.x - dragOffsetX;
+            layout->btnY       = mouse.y - dragOffsetY;
+            break;
+        case 4: /* Help */
+            layout->helpY = mouse.y - dragOffsetY;
+            break;
+        }
+    }
+
+    /* --- Release --- */
+    if (IsMouseButtonReleased(MOUSE_BUTTON_LEFT)) {
+        dragIndex = -1;
+    }
+
+    Color barFill = (dragIndex == 1) ? highlightColor : fillColor;
+
+    /* --- 0: Title --- */
+    {
+        Color f = (dragIndex == 0) ? highlightColor : fillColor;
+        Rectangle r = { (float)screenW / 2.0f - TITLE_W / 2.0f,
+                       layout->titleY, TITLE_W, TITLE_H };
+        draw_label("Title", r, f, borderColor);
+    }
+
+    /* --- 1: Bar group --- */
+    /* Percentage above bar (centered on bar's X) */
+    {
+        Rectangle r = { layout->barX + layout->barWidth / 2.0f - PCT_W / 2.0f,
+                       layout->barY - 40.0f, PCT_W, PCT_H };
+        draw_label("%", r, barFill, borderColor);
+    }
+    /* Elapsed time */
+    {
+        Rectangle r = { layout->barX - 90.0f, layout->barY,
+                       TIME_W, layout->barHeight };
+        draw_label("Time", r, barFill, borderColor);
+    }
+    /* Bar */
+    {
+        Rectangle r = { layout->barX, layout->barY,
+                       layout->barWidth, layout->barHeight };
+        draw_label("Bar", r, barFill, borderColor);
+    }
+    /* Remaining time */
+    {
+        Rectangle r = { layout->barX + layout->barWidth + 10.0f,
+                       layout->barY, TIME_W, layout->barHeight };
+        draw_label("Time", r, barFill, borderColor);
+    }
+
+    /* --- 2: Status --- */
+    {
+        Color f = (dragIndex == 2) ? highlightColor : fillColor;
+        Rectangle r = { (float)screenW / 2.0f - STATUS_W / 2.0f,
+                       layout->statusY, STATUS_W, STATUS_H };
+        draw_label("Status", r, f, borderColor);
+    }
+
+    /* --- 3: Play button --- */
+    {
+        float cx = layout->btnCenterX;
+        float cy = layout->btnY;
+        float r  = layout->btnRadius;
+        Color  f = (dragIndex == 3) ? highlightColor : fillColor;
+        DrawCircle((int)cx, (int)cy, r, f);
+        DrawCircleLines((int)cx, (int)cy, r, borderColor);
+        float half = r * 0.5f;
+        Vector2 v1 = { cx - half * 0.7f, cy - half };
+        Vector2 v2 = { cx - half * 0.7f, cy + half };
+        Vector2 v3 = { cx + half * 0.8f, cy };
+        DrawTriangle(v1, v2, v3, labelColor);
+    }
+
+    /* --- 4: Help --- */
+    {
+        Color f = (dragIndex == 4) ? highlightColor : fillColor;
+        Rectangle r = { 40.0f, layout->helpY, HELP_W, HELP_H };
+        draw_label("Help", r, f, borderColor);
+    }
+}
diff --git a/src/layout_editor.h b/src/layout_editor.h
new file mode 100644
index 0000000..a05cca7
--- /dev/null
+++ b/src/layout_editor.h
@@ -0,0 +1,5 @@
+#pragma once
+#include "config.h"
+
+void layout_editor_init(void);
+void layout_editor_draw(const char *exePath, UILayout *layout);
diff --git a/src/main.c b/src/main.c
index 7f3d1d8..f07b9a0 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4,6 +4,8 @@
 #include <ctype.h>
 #include <stdio.h>
 #include "config.h"
+#include "layout_editor.h"
+#include "raygui.h"
 #include "font_data.h"
 
 #ifdef PLATFORM_LINUX
@@ -54,6 +56,10 @@ static Color btnHoverColor;
 
 static UILayout layout;
 
+static int activeTab = 0;
+static int prevTab = 0;
+static char exeDir[512];
+
 static int strcasecmp_ext(const char *a, const char *b)
 {
     while (*a && *b) {
@@ -352,6 +358,8 @@ static void update_frame(void)
     }
 #endif
 
+    if (activeTab == 0)
+    {
     /* --- Button clicks --- */
     if (state.loaded)
     {
@@ -506,6 +514,7 @@ static void update_frame(void)
             }
         }
     }
+    }
 
     /* --- Music stream update --- */
     if (state.loaded)
@@ -555,10 +564,20 @@ static void update_frame(void)
         }
     }
 
+    /* --- Save layout on tab switch --- */
+    if (prevTab == 1 && activeTab == 0) {
+        config_save(exeDir, &layout);
+    }
+    prevTab = activeTab;
+
     /* --- Drawing --- */
     BeginDrawing();
     ClearBackground(bgColor);
 
+    char *tabNames[] = { "Player", "Layout" };
+    GuiTabBar((Rectangle){ 0, 10, SCREEN_W, 32 }, tabNames, 2, &activeTab);
+
+    if (activeTab == 0) {
     if (state.loaded)
     {
         draw_text_centered(font, state.filename, layout.titleY, szFont, mutedColor);
@@ -693,6 +712,10 @@ static void update_frame(void)
         }
     }
 
+    } else {
+        layout_editor_draw(exeDir, &layout);
+    }
+
     EndDrawing();
 }
 
@@ -744,6 +767,21 @@ int main(void)
         readlink("/proc/self/exe", exePath, sizeof(exePath) - 1);
 #endif
         config_load(exePath, &layout);
+
+        {
+            const char *lastSlash = strrchr(exePath, '/');
+            if (lastSlash) {
+                size_t len = (size_t)(lastSlash - exePath);
+                if (len >= sizeof(exeDir)) len = sizeof(exeDir) - 1;
+                memcpy(exeDir, exePath, len);
+                exeDir[len] = '\0';
+            } else {
+                exeDir[0] = '.';
+                exeDir[1] = '\0';
+            }
+        }
+
+        layout_editor_init();
     }
 
 #ifdef PLATFORM_WEB