public boolean isOverwriteMode()
    {
        return hexEditControl == null || hexEditControl.isOverwriteMode();

    }
Tells whether the input is in overwrite or insert mode

@return true: overwriting, false: inserting
plugins/org.jkiss.dbeaver.ui.editors.hex/src/org/jkiss/dbeaver/ui/editors/binary/HexManager.java