init header components

src/app/browser/header/subject/description.rs

@@ -0,0 +1,49 @@
+use gtk::Label;
+use gtk::prelude::WidgetExt;
+
+pub fn new() -> Label
+{
+    let description = Label::builder()
+
+        .css_classes(
+            [
+                "subtitle"
+            ]
+        )
+
+        .single_line_mode(
+            true
+        )
+
+        .ellipsize(
+            gtk::pango::EllipsizeMode::End
+        )
+
+        .build();
+
+    update(
+        &description,
+        "" // @TODO
+    );
+
+    return description;
+}
+
+pub fn update(
+    description: &Label,
+    text: &str
+) {
+    description.set_text(
+        text
+    );
+
+    if text.is_empty()
+    {
+        description.hide();
+    }
+
+    else
+    {
+        description.show();
+    }
+}