Manual implementation

- Added manual implementation to allow the property to be set to None.

src/app/settings.rs

@@ -26,7 +26,7 @@ pub struct Settings {
     pub(crate) default_font: Font,
 
     /// Name of the icon theme to search by default.
-    #[setters(into, strip_option)]
+    #[setters(skip)]
     pub(crate) default_icon_theme: Option<String>,
 
     /// Default size of fonts.
@@ -53,6 +53,19 @@ pub struct Settings {
     pub(crate) transparent: bool,
 }
 
+impl Settings {
+    /// Sets the default icon theme, passing an empty string will unset the theme.
+    pub fn default_icon_theme(mut self, value: impl Into<String>) -> Self {
+        let value: String = value.into();
+        self.default_icon_theme = if value.is_empty() {
+            None
+        } else {
+            Some(value.to_string())
+        };
+        self
+    }
+}
+
 impl Default for Settings {
     fn default() -> Self {
         Self {