Change the number in the Tab Width text field in the gray tab properties area of the tab you want to resize.
This is how tab widths work:
- Each tab may contain no charts or many charts.
- Each chart has a width attribute.
- The charts will fall onto the tab from left to right until their widths add up to be greater than the tab width that they're on.
- The charts will wrap to the next line when the sum of their widths for that row is greater than the tab width that they're on.