diff --git a/xo-imgui/example/ex4a/VulkanApp.cpp b/xo-imgui/example/ex4a/VulkanApp.cpp
index d25ca30e..0da4b4b2 100644
--- a/xo-imgui/example/ex4a/VulkanApp.cpp
+++ b/xo-imgui/example/ex4a/VulkanApp.cpp
@@ -568,4 +568,59 @@ MinimalImGuiVulkan::draw_frame()
     this->current_frame_ = (current_frame_ + 1) % MAX_FRAMES_IN_FLIGHT;
 }
 
+void
+MinimalImGuiVulkan::record_command_buffer(VkCommandBuffer cmdbuf, uint32_t image_ix)
+{
+    VkCommandBufferBeginInfo begin_info{};
+    begin_info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
+
+    if (vkBeginCommandBuffer(cmdbuf, &begin_info) != VK_SUCCESS) {
+        throw std::runtime_error("Failed to begin recording command buffer!");
+    }
+
+    VkRenderPassBeginInfo render_pass_info{};
+    render_pass_info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
+    render_pass_info.renderPass = render_pass_;
+    render_pass_info.framebuffer = framebuffers_[image_ix];
+    render_pass_info.renderArea.offset = {0, 0};
+    render_pass_info.renderArea.extent = swapchain_extent_;
+
+    VkClearValue clear_color = {{{0.0f, 0.0f, 0.0f, 1.0f}}};
+    render_pass_info.clearValueCount = 1;
+    render_pass_info.pClearValues = &clear_color;
+
+    vkCmdBeginRenderPass(cmdbuf, &render_pass_info, VK_SUBPASS_CONTENTS_INLINE);
+
+    // Start the Dear ImGui frame
+    {
+        ImGui_ImplVulkan_NewFrame();
+        ImGui_ImplSDL2_NewFrame();
+        ImGui::NewFrame();
+
+        // Create a simple ImGui window
+        ImGui::Begin("Hello, Vulkan + SDL2!");
+        ImGui::Text("This is a minimal ImGui + Vulkan + SDL2 example!");
+        static float f = 0.0f;
+        static int counter = 0;
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
+        if (ImGui::Button("Button"))
+            counter++;
+        ImGui::SameLine();
+        ImGui::Text("counter = %d", counter);
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+        ImGui::End();
+
+        // Rendering
+        ImGui::Render();
+        ImDrawData* draw_data = ImGui::GetDrawData();
+        ImGui_ImplVulkan_RenderDrawData(draw_data, cmdbuf);
+
+    }
+    vkCmdEndRenderPass(cmdbuf);
+
+    if (vkEndCommandBuffer(cmdbuf) != VK_SUCCESS) {
+        throw std::runtime_error("Failed to record command buffer!");
+    }
+}
+
 /* end VulkanApp.cpp */
diff --git a/xo-imgui/example/ex4a/VulkanApp.hpp b/xo-imgui/example/ex4a/VulkanApp.hpp
index 3024afd8..759f7bcb 100644
--- a/xo-imgui/example/ex4a/VulkanApp.hpp
+++ b/xo-imgui/example/ex4a/VulkanApp.hpp
@@ -117,56 +117,8 @@ private:
      */
     void draw_frame();
 
-    void record_command_buffer(VkCommandBuffer commandBuffer, uint32_t imageIndex) {
-        VkCommandBufferBeginInfo beginInfo{};
-        beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
-
-        if (vkBeginCommandBuffer(commandBuffer, &beginInfo) != VK_SUCCESS) {
-            throw std::runtime_error("Failed to begin recording command buffer!");
-        }
-
-        VkRenderPassBeginInfo renderPassInfo{};
-        renderPassInfo.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
-        renderPassInfo.renderPass = render_pass_;
-        renderPassInfo.framebuffer = framebuffers_[imageIndex];
-        renderPassInfo.renderArea.offset = {0, 0};
-        renderPassInfo.renderArea.extent = swapchain_extent_;
-
-        VkClearValue clearColor = {{{0.0f, 0.0f, 0.0f, 1.0f}}};
-        renderPassInfo.clearValueCount = 1;
-        renderPassInfo.pClearValues = &clearColor;
-
-        vkCmdBeginRenderPass(commandBuffer, &renderPassInfo, VK_SUBPASS_CONTENTS_INLINE);
-
-        // Start the Dear ImGui frame
-        ImGui_ImplVulkan_NewFrame();
-        ImGui_ImplSDL2_NewFrame();
-        ImGui::NewFrame();
-
-        // Create a simple ImGui window
-        ImGui::Begin("Hello, Vulkan + SDL2!");
-        ImGui::Text("This is a minimal ImGui + Vulkan + SDL2 example!");
-        static float f = 0.0f;
-        static int counter = 0;
-        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
-        if (ImGui::Button("Button"))
-            counter++;
-        ImGui::SameLine();
-        ImGui::Text("counter = %d", counter);
-        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
-        ImGui::End();
-
-        // Rendering
-        ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        ImGui_ImplVulkan_RenderDrawData(draw_data, commandBuffer);
-
-        vkCmdEndRenderPass(commandBuffer);
-
-        if (vkEndCommandBuffer(commandBuffer) != VK_SUCCESS) {
-            throw std::runtime_error("Failed to record command buffer!");
-        }
-    }
+    /* record draw instructions into cmdbuf, framebuffers_[image_ix] */
+    void record_command_buffer(VkCommandBuffer commandBuffer, uint32_t image_ix);
 
     void recreate_swapchain() {
         // handle window minimization: wait until window has valid size