Hello,
in my current project, I need finer control over the ground pour, specifically, I need to be able to block it in "inner parts" of the layout (ie, like an island). The idea is that a boost converter IC's ground layout is specific in how the power ground should be connected to signal ground.
My solution right now is to use a copper area and use the clearances to block out the ground, but this isn't ideal.
Brand new interactions and interfaces. 
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Hi
How about changing the clearance of the copper area?
Hi there,
first thing I did, but the effects of that affect the entire ground pour, and leads to even more problems, such as ground failing to pour in otherwise accessible (and desirable) areas.
This solid region you can set as cutout. there is no more good idea to solve your problem.
The problem with a solid area set as a cutout is that it leaves an isolated loop of track. This can make defining a copper free area even more complicated.
This is an example of a board with a small copper area assigned to the 4V5V net on the top layer:
Now the same thing with a small triangular solid region set as cutout and given no net name:
Setting the net name of the solid region to the same as that of the copper area (4V5V) causes the whole region to be flooded: