Merge 2 gui builders

src/builder/builder.rs

@@ -1,5 +1,5 @@
 use crate::prelude::*;
-use anyhow::Result;
+use anyhow::{bail, Result};
 
 use assetpath::AssetPath;
 
@@ -29,7 +29,7 @@ impl GuiBuilder {
             path,
         )?;
 
-        Self::_new(gui_handler, validator)
+        Ok(Arc::new(Self::_new(gui_handler, validator)?))
     }
 
     pub fn from_str(gui_handler: &Arc<GuiHandler>, s: &str) -> Result<Arc<Self>> {
@@ -39,11 +39,49 @@ impl GuiBuilder {
             s,
         )?;
 
-        Self::_new(gui_handler, validator)
+        Ok(Arc::new(Self::_new(gui_handler, validator)?))
+    }
+
+    pub fn merge<'a>(
+        gui_handler: &Arc<GuiHandler>,
+        pathes: impl IntoIterator<Item = &'a AssetPath>,
+    ) -> Result<Arc<Self>> {
+        let mut me = Self {
+            grids: Default::default(),
+            default_select: Default::default(),
+
+            ids: Default::default(),
+
+            decline_callback: Default::default(),
+        };
+
+        for path in pathes.into_iter() {
+            let validator = Validator::new(
+                #[cfg(feature = "audio")]
+                gui_handler,
+                path,
+            )?;
+
+            let builder = Self::_new(gui_handler, validator)?;
+
+            me.grids.extend(builder.grids);
+
+            if me.default_select.is_some() && builder.default_select.is_some() {
+                bail!("multiple default selects are not supported!");
+            }
+
+            if builder.default_select.is_some() {
+                me.default_select = builder.default_select;
+            }
+
+            me.ids.extend(builder.ids);
+        }
+
+        Ok(Arc::new(me))
     }
 
     #[inline]
-    fn _new(gui_handler: &Arc<GuiHandler>, validator: Validator) -> Result<Arc<Self>> {
+    fn _new(gui_handler: &Arc<GuiHandler>, validator: Validator) -> Result<Self> {
         let root = validator.root();
 
         let mut ids = HashMap::new();
@@ -71,14 +109,14 @@ impl GuiBuilder {
 
         Self::connect_custom_neighbours(&ids, custom_neighbours)?;
 
-        Ok(Arc::new(GuiBuilder {
+        Ok(GuiBuilder {
             grids,
             default_select: opt_default_select,
 
             ids,
 
             decline_callback: RwLock::new(None),
-        }))
+        })
     }
 
     pub(crate) fn connect_custom_neighbours(