diff --git a/source/nanogui/sdlapp.d b/source/nanogui/sdlapp.d
index b9ffd7b..7f46156 100644
--- a/source/nanogui/sdlapp.d
+++ b/source/nanogui/sdlapp.d
@@ -127,7 +127,7 @@ class SdlApp
 	}
 	auto onResize() { return _onResize; }
 
-	alias OnKeyboardChar = void delegate(dchar ch);
+	alias OnKeyboardChar = bool delegate(dchar ch);
 	private OnKeyboardChar _onKeyboardChar;
 	void onKeyboardChar(OnKeyboardChar handler)
 	{
diff --git a/source/nanogui/sdlbackend.d b/source/nanogui/sdlbackend.d
index bee5c63..4e09fdd 100644
--- a/source/nanogui/sdlbackend.d
+++ b/source/nanogui/sdlbackend.d
@@ -144,6 +144,11 @@ class SdlBackend : Screen
 			return super.mouseButtonCallbackEvent(btn, action, modifiers, Clock.currTime.stdTime);
 		};
 
+		_sdlApp.onKeyboardChar = delegate(dchar codepoint)
+		{
+			return keyboardCharacterEvent(codepoint);
+		};
+
 		_sdlApp.onClose = ()
 		{
 			if (_onClose)
diff --git a/source/nanogui/slider.d b/source/nanogui/slider.d
index d474d10..c9a132a 100644
--- a/source/nanogui/slider.d
+++ b/source/nanogui/slider.d
@@ -13,7 +13,7 @@ import std.algorithm : min, max;
 import arsd.nanovega;
 import nanogui.widget : Widget;
 import nanogui.common : Vector2i, MouseButton, Color, boxGradient, 
-	fillColor, Vector2f, radialGradient, linearGradient;
+	fillColor, Vector2f, radialGradient, linearGradient, NanoContext;
 
 /// Fractional slider widget with mouse control
 class Slider(T) : Widget {
@@ -170,7 +170,7 @@ public:
 		return true;
 	}
 
-	override void draw(NanoContext ctx)
+	override void draw(ref NanoContext ctx)
 	{
 		Vector2f center = cast(Vector2f) mPos + 0.5f * cast(Vector2f) mSize;
 		float kr = cast(int) (mSize.y * 0.4f);