diff --git a/.gitignore b/.gitignore
index ea8c4bf..a5ff07f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,8 @@
 /target
+
+
+# Added by cargo
+#
+# already existing elements were commented out
+
+#/target
diff --git a/src/.engine.rs.swp b/src/.engine.rs.swp
deleted file mode 100644
index ec956c9..0000000
Binary files a/src/.engine.rs.swp and /dev/null differ
diff --git a/src/.main.rs.swp b/src/.main.rs.swp
new file mode 100644
index 0000000..c52d682
Binary files /dev/null and b/src/.main.rs.swp differ
diff --git a/src/engine.rs b/src/engine.rs
index ab92677..a854edf 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -8,20 +8,20 @@ pub trait InputEngine {
    fn get(&mut self) -> Vec<char>;
 }
 
-pub fn build_input_engine(cfg: &Engine) -> impl InputEngine {
+pub fn build_input_engine(cfg: &Engine) -> Box<dyn InputEngine> {
    match cfg.name.as_str() {
       "stdin" => {
-         return InputEngineStdin{};
+         return Box::new(InputEngineStdin{});
       },
       "kafka" => {
-         return build_input_engine_kafka(&cfg).unwrap();
+         return Box::new(build_input_engine_kafka(&cfg).unwrap());
       },
-      "udp" => return build_input_engine_udp(&cfg).unwrap(),
-      "device" => return build_input_engine_device(&cfg).unwrap(),
+      "udp" => return Box::new(build_input_engine_udp(&cfg).unwrap()),
+      "device" => return Box::new(build_input_engine_device(&cfg).unwrap()),
       _ => {},
    };
    assert!(false);
-   InputEngineStdin{}
+   Box::new(InputEngineStdin{})
 }
 
 struct InputEngineDevice {
@@ -191,14 +191,14 @@ pub trait OutputEngine {
    fn put(&mut self, v: Vec<char>);
 }
 
-pub fn build_output_engine(cfg: &Engine) -> impl OutputEngine {
+pub fn build_output_engine(cfg: &Engine) -> Box<dyn OutputEngine> {
    if cfg.name.as_str() == "stdout" {
-      return OutputEngineStdout{};
+      return Box::new(OutputEngineStdout{});
    } else if cfg.name.as_str() == "udp" {
-      return build_output_engine_udp(&cfg).unwrap();
+      return Box::new(build_output_engine_udp(&cfg).unwrap());
    }
    assert!(false);
-   OutputEngineStdout{}
+   Box::new(OutputEngineStdout{})
 }
 
 struct OutputEngineStdout {}
diff --git a/src/gui.rs b/src/gui.rs
index 2c4241a..5669825 100644
--- a/src/gui.rs
+++ b/src/gui.rs
@@ -7,7 +7,7 @@ use iced::{Alignment, Element, Application, Settings, Subscription, Theme, Comma
 
 use crate::engine::OutputEngine;
 
-pub fn main(outputEngine: &impl OutputEngine) -> iced::Result {
+pub fn main(outputEngine: &(impl OutputEngine + ?Sized)) -> iced::Result {
    let settings = Settings{
       flags: Flags {
          //outputEngine: outputEngine,
diff --git a/src/main.rs b/src/main.rs
index 2d25dc0..3237d89 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,13 +2,11 @@ mod config;
 mod engine;
 mod gui;
 
-use crate::engine::{InputEngine, OutputEngine};
-
 fn main() {
    let cfg = config::build_config().unwrap();
    if cfg.streams.input.engine.name == "gui" {
       let mut output_engine = engine::build_output_engine(&cfg.streams.output.engine);
-      gui::main(&output_engine).unwrap();
+      gui::main(&*output_engine).unwrap();
    } else {
       main_cli(cfg);
    }