diff --git a/Cargo.toml b/Cargo.toml
index 6687e54bc..d9c66c4ce 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,7 @@ libc = "^0.2.23"
 gdk-sys = { git = "https://github.com/gtk-rs/sys" }
 gtk-sys = { git = "https://github.com/gtk-rs/sys" }
 glib = { git = "https://github.com/gtk-rs/glib.git" }
+glib-sys = { git = "https://github.com/gtk-rs/sys" }
 ffi = "^0.0.2"
 flexi_logger = "^0.5.1"
 log = "^0.3.8"
diff --git a/src/app_state.rs b/src/app_state.rs
index 1813314f5..af6af5bbf 100644
--- a/src/app_state.rs
+++ b/src/app_state.rs
@@ -1,10 +1,14 @@
 use gtk;
 
+use alsa::poll::PollDescriptors;
 use alsa::card::Card;
 use alsa::mixer::{Mixer, SelemId, Selem};
 use audio;
 use errors::*;
 
+// TODO: fix import
+use libc::pollfd;
+
 pub struct AppS {
     /* we keep this to ensure the lifetime is across the whole application */
     pub status_icon: gtk::StatusIcon,
@@ -12,10 +16,13 @@ pub struct AppS {
     pub builder_popup: gtk::Builder,
 }
 
+// TODO: implement free/destructor
 pub struct AlsaCard {
-    card: Card,
-    mixer: Mixer,
-    selem_id: SelemId,
+    _cannot_construct: (),
+    pub card: Card,
+    pub mixer: Mixer,
+    pub selem_id: SelemId,
+    pub watch_ids: Vec<pollfd>,
 }
 
 impl AlsaCard {
@@ -35,11 +42,15 @@ impl AlsaCard {
             elem_name.unwrap_or(String::from("Master")),
         ).unwrap()
             .get_id();
+        let vec_pollfd = PollDescriptors::get(&mixer)?;
+        // let watch_ids =
 
         return Ok(AlsaCard {
+            _cannot_construct: (),
             card: card,
             mixer: mixer,
             selem_id: selem_id,
+            watch_ids: vec![],
         });
     }
 
@@ -53,6 +64,10 @@ impl AlsaCard {
         return audio::get_vol(&self.selem());
     }
 
+    pub fn set_vol(&self, new_vol: f64) -> Result<()> {
+        return audio::set_vol(&self.selem(), new_vol);
+    }
+
     pub fn has_mute(&self) -> bool {
         return audio::has_mute(&self.selem());
     }
@@ -65,3 +80,19 @@ impl AlsaCard {
         return audio::set_mute(&self.selem(), mute);
     }
 }
+
+pub enum AudioUser {
+    AudioUserUnknown,
+    AudioUserPopup,
+    AudioUserTrayIcon,
+    AudioUserHotkeys,
+}
+
+enum AudioSignal {
+    AudioNoCard,
+    AudioCardInitialized,
+    AudioCardCleanedUp,
+    AudioCardDisconnected,
+    AudioCardError,
+    AudioValuesChanged,
+}
diff --git a/src/audio.rs b/src/audio.rs
index 81097fe9a..44cdb859c 100644
--- a/src/audio.rs
+++ b/src/audio.rs
@@ -1,13 +1,18 @@
 extern crate alsa;
-extern crate libc;
+extern crate glib_sys;
 
 use self::alsa::card::Card;
 use self::alsa::mixer::{Mixer, Selem, Elem};
 use alsa::mixer::SelemChannelId::*;
 use std::iter::Map;
-use self::libc::c_int;
+use libc::c_int;
+use libc::c_uint;
+use libc::c_void;
 use errors::*;
 use std::convert::From;
+use libc::pollfd;
+use app_state;
+use std::cell::RefCell;
 
 
 
@@ -60,15 +65,41 @@ pub fn get_selem_by_name(mixer: &Mixer, name: String) -> Result<Selem> {
     bail!("Not found a matching selem named {}", name);
 }
 
+pub fn vol_to_percent(vol: i64, range: (i64, i64)) -> f64 {
+    let (min, max) = range;
+    return ((vol - min) as f64) / ((max - min) as f64) * 100.0;
+}
+
+pub fn percent_to_vol(vol: f64, range: (i64, i64)) -> i64 {
+    let (min, max) = range;
+    let _v = vol / 100.0 * ((max - min) as f64) + (min as f64);
+    /* TODO: precision? Use direction. */
+    return _v as i64;
+}
+
 pub fn get_vol(selem: &Selem) -> Result<f64> {
-    let (min, max) = selem.get_playback_volume_range();
+    let range = selem.get_playback_volume_range();
     let volume = selem.get_playback_volume(FrontRight).map(|v| {
-        return ((v - min) as f64) / ((max - min) as f64) * 100.0;
+        return vol_to_percent(v, range);
     });
 
     return volume.cherr();
 }
 
+pub fn set_vol(selem: &Selem, new_vol: f64) -> Result<()> {
+    /* auto-unmute */
+    if get_mute(selem)? {
+        set_mute(selem, false)?;
+    }
+
+    let range = selem.get_playback_volume_range();
+    selem.set_playback_volume_all(
+        percent_to_vol(new_vol, range),
+    )?;
+
+    return Ok(());
+}
+
 pub fn has_mute(selem: &Selem) -> bool {
     return selem.has_playback_switch();
 }
@@ -83,3 +114,37 @@ pub fn set_mute(selem: &Selem, mute: bool) -> Result<()> {
     let _ = selem.set_playback_switch_all(!mute as i32)?;
     return Ok(());
 }
+
+
+
+/* GIO */
+
+pub fn watch_poll_descriptors(
+    polls: Vec<pollfd>,
+    acard: RefCell<app_state::AlsaCard>,
+) -> Vec<c_uint> {
+    let mut watch_ids: Vec<c_uint> = vec![];
+    for poll in polls {
+        unsafe {
+            let gioc = glib_sys::g_io_channel_unix_new(poll.fd);
+            watch_ids.push(glib_sys::g_io_add_watch(
+                gioc,
+                glib_sys::GIOCondition::from_bits_truncate(
+                    glib_sys::G_IO_IN.bits() | glib_sys::G_IO_ERR.bits(),
+                ),
+                Some(watch_cb),
+                acard.as_ptr() as glib_sys::gpointer,
+            ));
+        }
+    }
+
+    return vec![];
+}
+
+extern "C" fn watch_cb(
+    chan: *mut glib_sys::GIOChannel,
+    cond: glib_sys::GIOCondition,
+    data: glib_sys::gpointer,
+) -> glib_sys::gboolean {
+    return true as glib_sys::gboolean;
+}
diff --git a/src/gui_callbacks.rs b/src/gui_callbacks.rs
index c64e96e3d..ff807d5e1 100644
--- a/src/gui_callbacks.rs
+++ b/src/gui_callbacks.rs
@@ -63,6 +63,23 @@ fn init_popup_window(appstate: &AppS, rc_acard: Rc<RefCell<AlsaCard>>) {
         });
     }
 
+    /* vol_scale_adj.connect_value_changed */
+    {
+        let vol_scale_adj: Rc<gtk::Adjustment> =
+            Rc::new(
+                appstate.builder_popup.get_object("vol_scale_adj").unwrap(),
+            );
+
+        let card = rc_acard.clone();
+        let vol_scale = vol_scale_adj.clone();
+        vol_scale_adj.connect_value_changed(move |_| {
+            let acard = card.borrow();
+            let val = vol_scale.get_value();
+
+            try_w!(acard.set_vol(val));
+        });
+    }
+
     /* mute_check.connect_toggled */
     {
         let mute_check: gtk::CheckButton =
diff --git a/src/main.rs b/src/main.rs
index 4bd9e4460..d3bf9f32c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,6 +10,7 @@ extern crate gtk_sys;
 extern crate gdk;
 extern crate gdk_sys;
 extern crate alsa;
+extern crate libc;
 
 use gtk::prelude::*;
 use gdk_sys::GDK_KEY_Escape;