Inventory full error messqge

Time: multiple?
Frequency: all the time
World name: Shiva
Character name: Huryiade Masters
Retainer name: Any
NPC name: Any
Monster name: Any
Class/Level: Any
Party or solo: Unrelated
In-game time: Unrelated
Area and coordinates: Any
Housing: Unrelated
Steps:
1. Get a few of some iteme
2. Fill out all other slots of the inventory
3. Try adding more of the first item.

This happens all the time when trying to accept quest rewards (any quest, even hunting quests from Retainers), gathering or crafting. The only time i can add an item to a stack when inventory is full is when i'm buying said item or retrieving it from retainers (haven't tested mailed items).

This is seriously underwhelming user experience. Please fix this.