Trends: user configurable buffer around autozoom

When trends are autoscaled it appears that there is some logic applied to give a small buffer around the min and max value to ensure that the canvas is always larger than the trend.
 
As a data browser, I find that my trends are often scaled too large relative to the canvas, especially when there is not much movement in the data. To solve this problem, I would like to be able to configure my own canvas buffer sizes around the min and max.
 
For example, if my data is ranging from 0 to 1, the trend already displays from approximately -0.15 to 1.15, so maybe a 15% buffer is being applied. I would like to be able to set me own buffer value so that the scale would be, for example: -0.5 to 1.5.