Option to toggle hardware/software accelerated in config

cfg/config.go

@@ -19,6 +19,7 @@ highlight_line = true
 
 [render]
 aliased = true
+accelerated = true
 
 [theme]
 background = "0xfdf6e3"
@@ -57,7 +58,8 @@ func (c CursorConfig) GetCaretWidth() int {
 }
 
 type RenderConfig struct {
-	Aliased bool
+	Aliased     bool
+	Accelerated bool
 }
 
 // todo make this more extendable...

gui/buffer.go

@@ -329,7 +329,7 @@ func (b *Buffer) OnRender(ctx *sdl.Renderer) {
 	}
 
 	source := b.contents
-	if int(last_h) > 0 {
+	if int(last_h) > 0 && int(b.h) != 0 {
 		// work out how many lines can fit into
 		// the buffer, and set the source to
 		// slice the line buffer accordingly

main.go

@@ -117,7 +117,12 @@ func main() {
 		window.SetIcon(icon)
 	}
 
-	renderer, err := sdl.CreateRenderer(window, -1, sdl.RENDERER_ACCELERATED)
+	var mode uint32 = sdl.RENDERER_SOFTWARE
+	if config.Render.Accelerated {
+		mode = sdl.RENDERER_ACCELERATED
+	}
+
+	renderer, err := sdl.CreateRenderer(window, -1, mode)
 	if err != nil {
 		panic(err)
 	}