Element.kt: Keep the original x and y coordinates in memory

common/src/main/kotlin/fr/username404/snowygui/gui/Element.kt

@@ -8,9 +8,10 @@ import fr.username404.snowygui.Snowy
 
 fun interface Renderable { fun render(poseStack: PoseStack?) }
 abstract class Element(
-    var x: Double, var y: Double,
+    @JvmField val xOrigin: Double, @JvmField val yOrigin: Double,
     val width: Int, val height: Int
 ): Renderable {
+    var x = xOrigin; var y = yOrigin
     companion object Rendering {
         private var caughtError: Boolean = false
         @JvmStatic protected val tessellator: Tesselator = Tesselator.getInstance()