A spreadsheet system stores objects and formulas in the cells of the spreadsheet, along with metadata tags. Each cell may contain multiple objects (such as a group of photos). Drag-and-drop user actions automatically change tags associated with the moved objects based on a formula stored in the target cell if a forcing semantics mode is active, or automatically change a formula stored in the target cell if a non-forcing semantics mode is active. A formula in a cell selects a set of objects and may include set operators such as union, intersection, and minus. The formula may also filter sets to select a subset based on specified tag attributes of objects. The display of the spreadsheet adaptively selects a subset of objects to render in a cell and appropriately scales photos for optimal viewing.