Indicate whether an ability can actually do something for a selected activation type

src/main/java/com/minelittlepony/unicopia/ability/Ability.java

@@ -83,6 +83,15 @@ public interface Ability<T extends Hit> {
         return false;
     }
 
+    /**
+     * Checks whether this ability has any special actions for the given activation type.
+     * <p>
+     * The default is to only respond to press-and-hold actions.
+     */
+    default boolean acceptsQuickAction(Pony player, ActivationType type) {
+        return type == ActivationType.NONE;
+    }
+
     /**
      * Called on the client to get any data required for the quick action.
      *

src/main/java/com/minelittlepony/unicopia/ability/CarryAbility.java

@@ -63,6 +63,11 @@ public class CarryAbility implements Ability<Hit> {
         return false;
     }
 
+    @Override
+    public boolean acceptsQuickAction(Pony player, ActivationType type) {
+        return type == ActivationType.NONE || type == ActivationType.TAP;
+    }
+
     @Override
     public boolean apply(Pony iplayer, Hit data) {
         PlayerEntity player = iplayer.asEntity();

src/main/java/com/minelittlepony/unicopia/ability/EarthPonyKickAbility.java

@@ -116,6 +116,11 @@ public class EarthPonyKickAbility implements Ability<Pos> {
         return false;
     }
 
+    @Override
+    public boolean acceptsQuickAction(Pony player, ActivationType type) {
+        return type == ActivationType.NONE || type == ActivationType.TAP || type == ActivationType.DOUBLE_TAP;
+    }
+
     @Nullable
     @Override
     public Optional<Pos> prepare(Pony player) {

src/main/java/com/minelittlepony/unicopia/ability/FlyingDashAbility.java

@@ -49,6 +49,11 @@ public class FlyingDashAbility implements Ability<Hit> {
         return false;
     }
 
+    @Override
+    public boolean acceptsQuickAction(Pony player, ActivationType type) {
+        return type == ActivationType.NONE || type == ActivationType.TAP;
+    }
+
     @Override
     public boolean apply(Pony player, Hit data) {
         player.getPhysics().dashForward((float)player.asWorld().random.nextTriangular(2.5F, 0.3F));

src/main/java/com/minelittlepony/unicopia/ability/PegasusRainboomAbility.java

@@ -54,6 +54,11 @@ public class PegasusRainboomAbility implements Ability<Hit> {
         return false;
     }
 
+    @Override
+    public boolean acceptsQuickAction(Pony player, ActivationType type) {
+        return type == ActivationType.NONE || type == ActivationType.TAP;
+    }
+
     @Override
     public boolean apply(Pony player, Hit data) {
 

src/main/java/com/minelittlepony/unicopia/ability/UnicornDispellAbility.java

@@ -72,6 +72,11 @@ public class UnicornDispellAbility implements Ability<Pos> {
         return false;
     }
 
+    @Override
+    public boolean acceptsQuickAction(Pony player, ActivationType type) {
+        return type == ActivationType.NONE || (player.getSpecies() != Race.CHANGELING && type == ActivationType.TAP);
+    }
+
     @Override
     public double getCostEstimate(Pony player) {
         return getTarget(player)

src/main/java/com/minelittlepony/unicopia/ability/UnicornProjectileAbility.java

@@ -56,6 +56,11 @@ public class UnicornProjectileAbility extends AbstractSpellCastingAbility {
         return false;
     }
 
+    @Override
+    public boolean acceptsQuickAction(Pony player, ActivationType type) {
+        return type == ActivationType.NONE || type == ActivationType.DOUBLE_TAP;
+    }
+
     @Override
     public boolean apply(Pony player, Hit data) {
         TypedActionResult<CustomisedSpellType<?>> thrown = player.getCharms().getSpellInHand(true);

src/main/java/com/minelittlepony/unicopia/client/gui/Slot.java

@@ -1,10 +1,14 @@
 package com.minelittlepony.unicopia.client.gui;
 
+import java.util.Optional;
+
 import com.minelittlepony.unicopia.Unicopia;
+import com.minelittlepony.unicopia.ability.Ability;
 import com.minelittlepony.unicopia.ability.AbilityDispatcher;
 import com.minelittlepony.unicopia.ability.AbilitySlot;
 import com.minelittlepony.unicopia.ability.ActivationType;
 import com.minelittlepony.unicopia.client.KeyBindingsHandler;
+import com.minelittlepony.unicopia.client.UnicopiaClient;
 import com.mojang.blaze3d.systems.RenderSystem;
 
 import net.minecraft.client.gui.DrawContext;
@@ -132,7 +136,9 @@ class Slot {
 
     void renderLabel(DrawContext context, AbilityDispatcher abilities, float tickDelta) {
 
-        if (abilities.getStat(aSlot).getAbility(Unicopia.getConfig().hudPage.get()).isEmpty()) {
+        Optional<Ability<?>> ability = abilities.getStat(aSlot).getAbility(Unicopia.getConfig().hudPage.get());
+
+        if (ability.isEmpty()) {
             return;
         }
 
@@ -155,6 +161,9 @@ class Slot {
         ActivationType activation = KeyBindingsHandler.INSTANCE.getForcedActivationType();
         if (activation.isResult()) {
             label = label.append("+T" + activation.getTapCount());
+            if (!ability.get().acceptsQuickAction(UnicopiaClient.getClientPony(), activation)) {
+                label = label.formatted(Formatting.RED);
+            }
         }
 
         context.drawText(uHud.font, label, 0, 0, 0xFFFFFF, true);