The Pin UV Tool locks affected vertices so they cannot be modified. By default, pinned UVs appear blue. Ctrl select UVs to unfreeze them.
The following options appear in the Tool Settings window when you select Tools > Pin > .
Hotkey: B + drag or MMB-drag left/right to adjust the brush size.
Hotkey: M + drag or MMB-drag up/down to adjust the brush strength.
Controls the profile (cross-section) of the UV tools. Falloff controls how the tool's strength diminishes from the center of the brush towards its outer edge. The tool assigns a falloff value to each UV within the brush's radius depending on its distance from the center point. The farther a UV is from the center point, the more falloff is applied. The following falloff types use different methods to measure this distance. See also Adjust tool falloff.
(Default) Surface/Volume is a combination of Surface and Volume falloff types. To determine which vertices to affect, the brush walks along the surface until it reaches the end of the surface or the edge of its radius, whichever comes first. To determine the falloff values of each vertex, the brush draws a straight line from the center of the brush to each vertex.
Controls the profile (cross-section) of the UV tools. The falloff curve determines how the tool strength diminishes from the center towards its outer edge.
Constrains points to the Curve grid.
Saves the current falloff curve to the Custom Curve presets.
Lets you quickly set the Falloff curve by selecting from frequently used shapes.
Lets you quickly set the Curve by selecting from custom shapes.
Ctrl-click a custom curve image to delete it.