A Painter's Palette without any dyes.
A Painter's Palette with various dyes, the one in the middle represent the selected one.
The Painter's Palette contains an inventory capable of holding 4 drawing tools, and 27 dye (including modifiers and paper) items. Its inventory can only hold one item per slot.
To access it, either shift right-click while holding the item, or right-click the item while in an inventory.
While in the inventory, the slot where the Painter's Palette reside will be locked. Some items may be highlighted with a special border, indicating they are currently selected for drawing.
Selected items can be changed by middle-clicking on another item (or outside the GUI to select the pixel tool).
Right-clicking on a blackboard will draw on it as-if the selected items were in the player's hands.
When the item is selected in the hotbar, if you scroll while holding shift the selected color will be changed, the tool too if the control key is held.