Add breadcrumb trail widget (#884)

editor/src/messages/layout/layout_message_handler.rs

@@ -56,6 +56,12 @@ impl<F: Fn(&MessageDiscriminant) -> Vec<KeysGroup>> MessageHandler<LayoutMessage
 
 				#[remain::sorted]
 				match &mut widget_holder.widget {
+					Widget::BreadcrumbTrailButtons(breadcrumb_trail_buttons) => {
+						let update_value = value.as_u64().expect("BreadcrumbTrailButtons update was not of type: u64");
+
+						let callback_message = (breadcrumb_trail_buttons.on_update.callback)(&update_value);
+						responses.push_back(callback_message);
+					}
 					Widget::CheckboxInput(checkbox_input) => {
 						let update_value = value.as_bool().expect("CheckboxInput update was not of type: bool");
 						checkbox_input.checked = update_value;

editor/src/messages/layout/utility_types/layout_widget.rs

@@ -57,6 +57,7 @@ impl Layout {
 			for widget_holder in &mut widget_layout.iter_mut() {
 				// Handle all the widgets that have tooltips
 				let mut tooltip_shortcut = match &mut widget_holder.widget {
+					Widget::BreadcrumbTrailButtons(widget) => Some((&mut widget.tooltip, &mut widget.tooltip_shortcut)),
 					Widget::CheckboxInput(widget) => Some((&mut widget.tooltip, &mut widget.tooltip_shortcut)),
 					Widget::ColorInput(widget) => Some((&mut widget.tooltip, &mut widget.tooltip_shortcut)),
 					Widget::DropdownInput(widget) => Some((&mut widget.tooltip, &mut widget.tooltip_shortcut)),
@@ -295,6 +296,7 @@ impl<T> Default for WidgetCallback<T> {
 #[remain::sorted]
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub enum Widget {
+	BreadcrumbTrailButtons(BreadcrumbTrailButtons),
 	CheckboxInput(CheckboxInput),
 	ColorInput(ColorInput),
 	DropdownInput(DropdownInput),

editor/src/messages/layout/utility_types/widgets/button_widgets.rs

@@ -90,3 +90,22 @@ pub struct TextButton {
 	#[derivative(Debug = "ignore", PartialEq = "ignore")]
 	pub on_update: WidgetCallback<TextButton>,
 }
+
+#[derive(Clone, Serialize, Deserialize, Derivative, Default)]
+#[derivative(Debug, PartialEq)]
+#[serde(rename_all(serialize = "camelCase", deserialize = "camelCase"))]
+pub struct BreadcrumbTrailButtons {
+	pub labels: Vec<String>,
+
+	pub disabled: bool,
+
+	pub tooltip: String,
+
+	#[serde(skip)]
+	pub tooltip_shortcut: Option<ActionKeys>,
+
+	// Callbacks
+	#[serde(skip)]
+	#[derivative(Debug = "ignore", PartialEq = "ignore")]
+	pub on_update: WidgetCallback<u64>,
+}