A splitter is a visual separator between two element groups. It allows the user to resize the adjacent groups.
Is this the right control¶
Always put a splitter between aligned, resizable grouping controls to allow individualization for users.
Remember position and adjust control size accordingly on next login.
Define a minimum size for areas that cannot be undercut by users.
Make splitters at least 5 pixels wide so that they can be easily clicked by any input device.