diff --git a/passthrough.glsl b/passthrough.glsl
new file mode 100644
index 000000000..1102f4559
--- /dev/null
+++ b/passthrough.glsl
@@ -0,0 +1,4 @@
+void mainImage(out vec4 fragColor, in vec2 fragCoord) {
+    vec2 uv = fragCoord / iResolution.xy;
+    fragColor = vec4(texture(iChannel0, uv).rgb, 1.0);
+}
diff --git a/src/apprt/gtk/class/imgui_widget.zig b/src/apprt/gtk/class/imgui_widget.zig
index 50247fbf1..7961d7a83 100644
--- a/src/apprt/gtk/class/imgui_widget.zig
+++ b/src/apprt/gtk/class/imgui_widget.zig
@@ -317,9 +317,6 @@ pub const ImguiWidget = extern struct {
             cimgui.c.ImGui_Render();
         }
 
-        // OpenGL final render
-        gl.clearColor(0x28 / 0xFF, 0x2C / 0xFF, 0x34 / 0xFF, 1.0);
-        gl.clear(gl.c.GL_COLOR_BUFFER_BIT);
         cimgui.ImGui_ImplOpenGL3_RenderDrawData(cimgui.c.ImGui_GetDrawData());
 
         return @intFromBool(true);