diff --git a/demo/maps/src/jvmMain/kotlin/Main.kt b/demo/maps/src/jvmMain/kotlin/Main.kt
index d34bc9b..853c823 100644
--- a/demo/maps/src/jvmMain/kotlin/Main.kt
+++ b/demo/maps/src/jvmMain/kotlin/Main.kt
@@ -11,6 +11,10 @@ import androidx.compose.ui.unit.DpSize
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.window.Window
 import androidx.compose.ui.window.application
+import center.sciprog.attributes.AlphaAttribute
+import center.sciprog.attributes.Attributes
+import center.sciprog.attributes.ColorAttribute
+import center.sciprog.attributes.ZAttribute
 import center.sciprog.maps.compose.*
 import center.sciprog.maps.coordinates.*
 import center.sciprog.maps.features.*
diff --git a/maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/WebMercatorSpace.kt b/maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/WebMercatorSpace.kt
index 639fc84..b96233f 100644
--- a/maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/WebMercatorSpace.kt
+++ b/maps-kt-compose/src/commonMain/kotlin/center/sciprog/maps/compose/WebMercatorSpace.kt
@@ -85,6 +85,7 @@ public object WebMercatorSpace : CoordinateSpace<Gmc> {
     }
 
     override fun Gmc.isInsidePolygon(points: List<Gmc>): Boolean = points.zipWithNext().count { (left, right) ->
+        //using raytracing algorithm with the ray pointing "up"
         val longitudeRange = if(right.longitude >= left.longitude) {
             left.longitude..right.longitude
         } else {
diff --git a/maps-kt-features/src/commonMain/kotlin/center.sciprog.attributes/Attribute.kt b/maps-kt-features/src/commonMain/kotlin/center.sciprog.attributes/Attribute.kt
new file mode 100644
index 0000000..23bdd06
--- /dev/null
+++ b/maps-kt-features/src/commonMain/kotlin/center.sciprog.attributes/Attribute.kt
@@ -0,0 +1,29 @@
+package center.sciprog.attributes
+
+import androidx.compose.ui.graphics.Color
+import center.sciprog.maps.features.DragHandle
+import center.sciprog.maps.features.DragListener
+import center.sciprog.maps.features.FloatRange
+import center.sciprog.maps.features.MouseListener
+
+public interface Attribute<T>
+
+public object ZAttribute : Attribute<Float>
+
+public object DraggableAttribute : Attribute<DragHandle<Any>>
+
+public interface SetAttribute<V> : Attribute<Set<V>>
+
+public object DragListenerAttribute : SetAttribute<DragListener<Any>>
+
+public object ClickListenerAttribute : SetAttribute<MouseListener<Any>>
+
+public object HoverListenerAttribute : SetAttribute<MouseListener<Any>>
+
+public object VisibleAttribute : Attribute<Boolean>
+
+public object ColorAttribute : Attribute<Color>
+
+public object ZoomRangeAttribute : Attribute<FloatRange>
+
+public object AlphaAttribute : Attribute<Float>
diff --git a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Attributes.kt b/maps-kt-features/src/commonMain/kotlin/center.sciprog.attributes/Attributes.kt
similarity index 50%
rename from maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Attributes.kt
rename to maps-kt-features/src/commonMain/kotlin/center.sciprog.attributes/Attributes.kt
index 19176e3..8970989 100644
--- a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Attributes.kt
+++ b/maps-kt-features/src/commonMain/kotlin/center.sciprog.attributes/Attributes.kt
@@ -1,6 +1,7 @@
-package center.sciprog.maps.features
+package center.sciprog.attributes
 
 import androidx.compose.runtime.Stable
+import center.sciprog.maps.features.Feature
 import kotlin.jvm.JvmInline
 
 @Stable
@@ -9,16 +10,16 @@ public value class Attributes internal constructor(internal val map: Map<Attribu
     @Suppress("UNCHECKED_CAST")
     public operator fun <T> get(attribute: Attribute<T>): T? = map[attribute] as? T
 
-    public operator fun <T> Attribute<T>.invoke(value: T?): Attributes = withAttribute(this, value)
+//    public operator fun <T> Attribute<T>.invoke(value: T?): Attributes = withAttribute(this, value)
 
-    override fun toString(): String = "AttributeMap(value=${map.entries})"
+    override fun toString(): String = "Attributes(value=${map.entries})"
 
     public companion object {
         public val EMPTY: Attributes = Attributes(emptyMap())
     }
 }
 
-public fun <T, A : Attribute<T>> Attributes.withAttribute(
+public fun <T, A : Attribute<T>> Attributes.attribute(
     attribute: A,
     attrValue: T?,
 ): Attributes = Attributes(
@@ -29,6 +30,34 @@ public fun <T, A : Attribute<T>> Attributes.withAttribute(
     }
 )
 
+/**
+ * Add an element to a [SetAttribute]
+ */
+public fun <T, A : SetAttribute<T>> Attributes.addValue(
+    attribute: A,
+    attrValue: T,
+): Attributes {
+    val currentSet: Set<T> = get(attribute) ?: emptySet()
+    return Attributes(
+        map + (attribute to (currentSet + attrValue))
+    )
+}
+
+/**
+ * Remove an element from [SetAttribute]
+ */
+public fun <T, A : SetAttribute<T>> Attributes.removeValue(
+    attribute: A,
+    attrValue: T,
+): Attributes {
+    val currentSet: Set<T> = get(attribute) ?: emptySet()
+    return Attributes(
+        map + (attribute to (currentSet - attrValue))
+    )
+}
+
+
+
 public fun <T : Any, A : Attribute<T>> Attributes(
     attribute: A,
     attrValue: T,
diff --git a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Attribute.kt b/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Attribute.kt
deleted file mode 100644
index 73f6bdd..0000000
--- a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Attribute.kt
+++ /dev/null
@@ -1,23 +0,0 @@
-package center.sciprog.maps.features
-
-import androidx.compose.ui.graphics.Color
-
-public interface Attribute<T>
-
-public object ZAttribute : Attribute<Float>
-
-public object DraggableAttribute : Attribute<DragHandle<Any>>
-
-public object DragListenerAttribute : Attribute<Set<DragListener<Any>>>
-
-public object ClickListenerAttribute : Attribute<Set<MouseListener<Any>>>
-
-public object HoverListenerAttribute : Attribute<Set<MouseListener<Any>>>
-
-public object VisibleAttribute : Attribute<Boolean>
-
-public object ColorAttribute : Attribute<Color>
-
-public object ZoomRangeAttribute : Attribute<FloatRange>
-
-public object AlphaAttribute : Attribute<Float>
diff --git a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Feature.kt b/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Feature.kt
index cc05ef9..7c5c20e 100644
--- a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Feature.kt
+++ b/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/Feature.kt
@@ -14,6 +14,9 @@ import androidx.compose.ui.graphics.vector.rememberVectorPainter
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.DpSize
 import androidx.compose.ui.unit.dp
+import center.sciprog.attributes.Attributes
+import center.sciprog.attributes.ColorAttribute
+import center.sciprog.attributes.ZoomRangeAttribute
 
 public typealias FloatRange = ClosedFloatingPointRange<Float>
 
diff --git a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/FeatureGroup.kt b/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/FeatureGroup.kt
index c6bf469..aaa30cd 100644
--- a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/FeatureGroup.kt
+++ b/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/FeatureGroup.kt
@@ -13,6 +13,7 @@ import androidx.compose.ui.input.pointer.PointerEvent
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.DpSize
 import androidx.compose.ui.unit.dp
+import center.sciprog.attributes.*
 import kotlin.jvm.JvmInline
 
 @JvmInline
@@ -64,7 +65,7 @@ public data class FeatureGroup<T : Any>(
             if (feature is FeatureGroup<T>) {
                 feature.visitUntil(visitor)
             } else {
-                if (!visitor(this, key, feature)) return@forEach
+                if (!visitor(this, key, feature)) return@visitUntil
             }
         }
     }
@@ -79,7 +80,15 @@ public data class FeatureGroup<T : Any>(
     }
 
     public fun <F : Feature<T>, V> FeatureId<F>.attribute(key: Attribute<V>, value: V?): FeatureId<F> {
-        feature(this, get(this).withAttributes { withAttribute(key, value) })
+        feature(this, get(this).withAttributes { attribute(key, value) })
+        return this
+    }
+
+    /**
+     * Add multi-entry [SetAttribute] value
+     */
+    public fun <F : Feature<T>, V> FeatureId<F>.addAttribute(key: SetAttribute<V>, value: V): FeatureId<F> {
+        feature(this, get(this).withAttributes { addValue(key, value) })
         return this
     }
 
@@ -126,12 +135,9 @@ public data class FeatureGroup<T : Any>(
     public fun FeatureId<DraggableFeature<T>>.onDrag(
         listener: PointerEvent.(from: ViewPoint<T>, to: ViewPoint<T>) -> Unit,
     ) {
-        attribute(
+        addAttribute(
             DragListenerAttribute,
-            (getAttribute(this, DragListenerAttribute) ?: emptySet()) +
-                    DragListener { event, from, to ->
-                        event.listener(from as ViewPoint<T>, to as ViewPoint<T>)
-                    }
+            DragListener { event, from, to -> event.listener(from as ViewPoint<T>, to as ViewPoint<T>) }
         )
     }
 
@@ -139,21 +145,20 @@ public data class FeatureGroup<T : Any>(
     public fun <F : DomainFeature<T>> FeatureId<F>.onClick(
         onClick: PointerEvent.(click: ViewPoint<T>) -> Unit,
     ) {
-        attribute(
+        addAttribute(
             ClickListenerAttribute,
-            (getAttribute(this, ClickListenerAttribute) ?: emptySet()) +
-                    MouseListener { event, point -> event.onClick(point as ViewPoint<T>) }
+            MouseListener { event, point -> event.onClick(point as ViewPoint<T>) }
         )
+
     }
 
     @Suppress("UNCHECKED_CAST")
     public fun <F : DomainFeature<T>> FeatureId<F>.onHover(
         onClick: PointerEvent.(move: ViewPoint<T>) -> Unit,
     ) {
-        attribute(
+        addAttribute(
             HoverListenerAttribute,
-            (getAttribute(this, HoverListenerAttribute) ?: emptySet()) +
-                    MouseListener { event, point -> event.onClick(point as ViewPoint<T>) }
+            MouseListener { event, point -> event.onClick(point as ViewPoint<T>) }
         )
     }
 
diff --git a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/compositeFeatures.kt b/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/compositeFeatures.kt
index c39f879..a3143a7 100644
--- a/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/compositeFeatures.kt
+++ b/maps-kt-features/src/commonMain/kotlin/center/sciprog/maps/features/compositeFeatures.kt
@@ -1,5 +1,9 @@
 package center.sciprog.maps.features
 
+import center.sciprog.attributes.Attributes
+import center.sciprog.attributes.ZAttribute
+import center.sciprog.attributes.attribute
+
 
 public fun <T : Any> FeatureGroup<T>.draggableLine(
     aId: FeatureId<MarkerFeature<T>>,
@@ -16,7 +20,7 @@ public fun <T : Any> FeatureGroup<T>.draggableLine(
             get(bId).center,
             lineId?.id ?: id
         )
-        if (attributes != null) currentId.modifyAttributes { attributes.withAttribute(ZAttribute, -10f) }
+        if (attributes != null) currentId.modifyAttributes { attributes.attribute(ZAttribute, -10f) }
         lineId = currentId
         return currentId
     }
diff --git a/maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/compose/mapControls.kt b/maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/compose/mapControls.kt
index 30289c2..3622c22 100644
--- a/maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/compose/mapControls.kt
+++ b/maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/compose/mapControls.kt
@@ -7,6 +7,9 @@ import androidx.compose.ui.input.pointer.*
 import androidx.compose.ui.unit.DpOffset
 import androidx.compose.ui.unit.DpRect
 import androidx.compose.ui.unit.dp
+import center.sciprog.attributes.ClickListenerAttribute
+import center.sciprog.attributes.DraggableAttribute
+import center.sciprog.attributes.HoverListenerAttribute
 import center.sciprog.maps.features.*
 import kotlin.math.max
 import kotlin.math.min
@@ -94,9 +97,15 @@ public fun <T : Any> Modifier.mapControls(
                             val dragResult = config.dragHandle?.handle(event, dragStart, dragEnd)
                             if (dragResult?.handleNext == false) return@drag
 
+                            var continueAfter = true
+
                             features.forEachWithAttributeUntil(DraggableAttribute) { _, _, handler ->
-                                handler.handle(event, dragStart, dragEnd).handleNext
+                                handler.handle(event, dragStart, dragEnd).handleNext.also {
+                                    if (!it) continueAfter = false
+                                }
                             }
+
+                            if (!continueAfter) return@drag
                         }
 
                         if (event.buttons.isPrimaryPressed) {
diff --git a/maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/features/drawFeature.kt b/maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/features/drawFeature.kt
index 8c4aad8..a1c65ab 100644
--- a/maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/features/drawFeature.kt
+++ b/maps-kt-features/src/jvmMain/kotlin/center/sciprog/maps/features/drawFeature.kt
@@ -11,6 +11,8 @@ import androidx.compose.ui.graphics.drawscope.translate
 import androidx.compose.ui.graphics.nativeCanvas
 import androidx.compose.ui.graphics.painter.Painter
 import androidx.compose.ui.graphics.toArgb
+import center.sciprog.attributes.AlphaAttribute
+import center.sciprog.attributes.plus
 import org.jetbrains.skia.Font
 import org.jetbrains.skia.Paint
 import kotlin.math.PI
diff --git a/maps-kt-scheme/src/commonMain/kotlin/center/sciprog/maps/scheme/schemeFeatures.kt b/maps-kt-scheme/src/commonMain/kotlin/center/sciprog/maps/scheme/schemeFeatures.kt
index 5f6ae37..33acdf0 100644
--- a/maps-kt-scheme/src/commonMain/kotlin/center/sciprog/maps/scheme/schemeFeatures.kt
+++ b/maps-kt-scheme/src/commonMain/kotlin/center/sciprog/maps/scheme/schemeFeatures.kt
@@ -8,6 +8,8 @@ import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.DpSize
 import androidx.compose.ui.unit.dp
+import center.sciprog.attributes.Attributes
+import center.sciprog.attributes.ZAttribute
 import center.sciprog.maps.features.*
 
 internal fun Pair<Number, Number>.toCoordinates(): XY = XY(first.toFloat(), second.toFloat())