diff --git a/src/util.rs b/src/util.rs
index 08a6a4c..31c89c7 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -50,6 +50,48 @@ macro_rules! loop_select {
     }
 }
 
+/// Parse a string with a concrete set of options into some data-structure,
+/// and return a nicely formatted error message on invalid values. I.e.:
+/// ```rs
+/// let input = "up";
+/// enum_parse { "direction", input,
+///   "up" => Direction::Up,
+///   "down" => Direction::Down,
+/// }
+/// ```
+#[macro_export]
+macro_rules! enum_parse {
+    ($name:literal, $input:expr, $($($s:literal)|* => $val:expr),* $(,)?) => {
+        let input = $input;
+        match input {
+            $( $( $s )|* => Ok($val) ),*,
+            _ => Err(anyhow!(concat!("Couldn't parse ", $name, ": '{}'. Possible values are ", $($($s),*),*), input))
+        }
+    };
+}
+
+/// Compute the difference of two lists, returning a tuple of
+/// (
+///   elements that where in a but not in b,
+///   elements that where in b but not in a
+/// ).
+pub fn list_difference<'a, 'b, T: PartialEq>(a: &'a [T], b: &'b [T]) -> (Vec<&'a T>, Vec<&'b T>) {
+    let mut missing = Vec::new();
+    for elem in a {
+        if !b.contains(elem) {
+            missing.push(elem);
+        }
+    }
+
+    let mut new = Vec::new();
+    for elem in b {
+        if !a.contains(elem) {
+            new.push(elem);
+        }
+    }
+    (missing, new)
+}
+
 /// Joins two paths while keeping it somewhat pretty.
 /// If the second path is absolute, this will just return the second path.
 /// If it is relative, it will return the second path joined onto the first path, removing any `./` if present.
@@ -112,7 +154,6 @@ pub fn parse_duration(s: &str) -> Result<std::time::Duration> {
     }
 }
 
-
 pub trait IterAverage {
     fn avg(self) -> f32;
 }
diff --git a/src/widgets/widget_definitions.rs b/src/widgets/widget_definitions.rs
index 701f58c..a2bce03 100644
--- a/src/widgets/widget_definitions.rs
+++ b/src/widgets/widget_definitions.rs
@@ -1,6 +1,11 @@
 #![allow(clippy::option_map_unit_fn)]
 use super::{run_command, BuilderArgs};
-use crate::{config, eww_state, resolve_block, value::AttrVal, widgets::widget_node, util::parse_duration};
+use crate::{
+    config, enum_parse, eww_state, resolve_block,
+    util::{list_difference, parse_duration},
+    value::AttrVal,
+    widgets::widget_node,
+};
 use anyhow::*;
 use gdk::WindowExt;
 use glib;
@@ -275,11 +280,11 @@ fn build_gtk_revealer(bargs: &mut BuilderArgs) -> Result<gtk::Revealer> {
     let gtk_widget = gtk::Revealer::new();
     resolve_block!(bargs, gtk_widget, {
         // @prop transition - the name of the transition. Possible values: $transition
-        prop(transition: as_string) { gtk_widget.set_transition_type(parse_transition(&transition)?); },
+        prop(transition: as_string = "crossfade") { gtk_widget.set_transition_type(parse_transition(&transition)?); },
         // @prop reveal - sets if the child is revealed or not
         prop(reveal: as_bool) { gtk_widget.set_reveal_child(reveal); },
         // @prop duration - the duration of the reveal transition
-        prop(duration: as_string) { gtk_widget.set_transition_duration(parse_duration(&duration)?.as_millis() as u32); },
+        prop(duration: as_string = "500ms") { gtk_widget.set_transition_duration(parse_duration(&duration)?.as_millis() as u32); },
     });
     Ok(gtk_widget)
 }
@@ -568,36 +573,33 @@ fn build_gtk_calendar(bargs: &mut BuilderArgs) -> Result<gtk::Calendar> {
 
 /// @var orientation - "vertical", "v", "horizontal", "h"
 fn parse_orientation(o: &str) -> Result<gtk::Orientation> {
-    Ok(match o {
+    enum_parse! { "orientation", o,
         "vertical" | "v" => gtk::Orientation::Vertical,
         "horizontal" | "h" => gtk::Orientation::Horizontal,
-        _ => bail!(r#"Couldn't parse orientation: '{}'. Possible values are "vertical", "v", "horizontal", "h""#, o),
-    })
+    }
 }
 
 /// @var transition - "slideright", "slideleft", "slideup", "slidedown", "crossfade", "none"
 fn parse_transition(t: &str) -> Result<gtk::RevealerTransitionType> {
-    Ok(match t {
+    enum_parse! { "transition", t,
         "slideright" => gtk::RevealerTransitionType::SlideRight,
         "slideleft" => gtk::RevealerTransitionType::SlideLeft,
         "slideup" => gtk::RevealerTransitionType::SlideUp,
         "slidedown" => gtk::RevealerTransitionType::SlideDown,
-        "crossfade" => gtk::RevealerTransitionType::Crossfade,
+        "fade" | "crossfade" => gtk::RevealerTransitionType::Crossfade,
         "none" => gtk::RevealerTransitionType::None,
-        _ => bail!(r#"Couldn't parse transition: '{}'. Possible values are "slideright", "slideleft", "slideup", "slidedown", "crossfade" and "none" "#, t),
-    })
+    }
 }
 
 /// @var alignment - "fill", "baseline", "center", "start", "end"
 fn parse_align(o: &str) -> Result<gtk::Align> {
-    Ok(match o {
+    enum_parse! { "alignment", o,
         "fill" => gtk::Align::Fill,
         "baseline" => gtk::Align::Baseline,
         "center" => gtk::Align::Center,
         "start" => gtk::Align::Start,
         "end" => gtk::Align::End,
-        _ => bail!(r#"Couldn't parse alignment: '{}'. Possible values are "fill", "baseline", "center", "start", "end""#, o),
-    })
+    }
 }
 
 fn connect_first_map<W: IsA<gtk::Widget>, F: Fn(&W) + 'static>(widget: &W, func: F) {
@@ -610,25 +612,3 @@ fn connect_first_map<W: IsA<gtk::Widget>, F: Fn(&W) + 'static>(widget: &W, func:
         }
     });
 }
-
-/// Compute the difference of two lists, returning a tuple of
-/// (
-///   elements that where in a but not in b,
-///   elements that where in b but not in a
-/// ).
-fn list_difference<'a, 'b, T: PartialEq>(a: &'a [T], b: &'b [T]) -> (Vec<&'a T>, Vec<&'b T>) {
-    let mut missing = Vec::new();
-    for elem in a {
-        if !b.contains(elem) {
-            missing.push(elem);
-        }
-    }
-
-    let mut new = Vec::new();
-    for elem in b {
-        if !a.contains(elem) {
-            new.push(elem);
-        }
-    }
-    (missing, new)
-}