Add custom shader_version on glow renderer (#1993)

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/eframe/src/epi.rs

@@ -311,6 +311,13 @@ pub struct NativeOptions {
     ///
     /// Note: A [`NativeOptions`] clone will not include any `event_loop_builder` hook.
     pub event_loop_builder: Option<EventLoopBuilderHook>,
+
+    #[cfg(feature = "glow")]
+    /// Needed for cross compiling for VirtualBox VMSVGA driver with OpenGL ES 2.0 and OpenGL 2.1 which doesn't support SRGB texture.
+    /// See <https://github.com/emilk/egui/pull/1993>.
+    ///
+    /// For OpenGL ES 2.0: set this to [`egui_glow::ShaderVersion::Es100`] to solve blank texture problem (by using the "fallback shader").
+    pub shader_version: Option<egui_glow::ShaderVersion>,
 }
 
 #[cfg(not(target_arch = "wasm32"))]
@@ -350,6 +357,8 @@ impl Default for NativeOptions {
             default_theme: Theme::Dark,
             run_and_return: true,
             event_loop_builder: None,
+            #[cfg(feature = "glow")]
+            shader_version: None,
         }
     }
 }