[examples] Add shapes_outlines_thickness (#6037)

Add an example to demonstrate the new thickness behavior in `Draw*LinesEx()` functions.

examples/shapes/shapes_outlines_thickness.c

@@ -0,0 +1,78 @@
+/*******************************************************************************************
+*
+*   raylib [shapes] example - outlines thickness
+*
+*   Example complexity rating: [★☆☆☆] 1/4
+*
+*   Example originally created with raylib 6.1, last time updated with raylib 6.1
+*
+*   Example contributed by Matthew Roush (@MatthewRoush) and reviewed by Ramon Santamaria (@raysan5)
+*
+*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+*   BSD-like license that allows static linking with closed source software
+*
+*   Copyright (c) 2026 Matthew Roush (@MatthewRoush)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#define RAYGUI_IMPLEMENTATION
+#include "raygui.h"         // Required for GUI controls
+
+//------------------------------------------------------------------------------------
+// Program main entry point
+//------------------------------------------------------------------------------------
+int main(void)
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    const int screenWidth = 800;
+    const int screenHeight = 450;
+
+    InitWindow(screenWidth, screenHeight, "raylib [shapes] example - outlines thickness");
+
+    float thick = 5.0f;
+
+    SetTargetFPS(60);
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        // TODO: Update variables / Implement example logic at this point
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+
+            GuiSliderBar((Rectangle){ 290, 50, 220, 24 }, "Thickness", TextFormat("%.2f", thick), &thick, -30.0f, 30.0f);
+
+            DrawRectangle(35, 180, 220, 220, LIGHTGRAY);
+            DrawRectangleLinesEx((Rectangle){ 35, 180, 220, 220 }, thick, BLUE);
+            DrawText("DrawRectangleLinesEx()", 35, 160, 10, BLACK);
+
+            DrawRectangleRounded((Rectangle){ 290, 180, 220, 220 }, 0.2f, 9, LIGHTGRAY);
+            DrawRectangleRoundedLinesEx((Rectangle){ 290, 180, 220, 220 }, 0.2f, 9, thick, BLUE);
+            DrawText("DrawRectangleRoundedLinesEx()", 290, 160, 10, BLACK);
+
+            DrawCircle(655, 290, 110, LIGHTGRAY);
+            DrawCircleLinesEx((Vector2){ 655, 290 }, 110, thick, BLUE);
+            DrawText("DrawCircleLinesEx()", 545, 160, 10, BLACK);
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}