Describe the bug
When the option Show labels is disabled, the taskbar progress gets this weird "margin" and does not fill the whole button. This makes the progress indicator really difficult to see.

Steps to reproduce

1. Run an application which shows some progress on the taskbar (e.g. download something in Chrome)
2. Disable Show labels inside of the Cairo settings

Expected behavior
The progress should fill the whole button as it does when Show labels is enabled.

System information:

• Windows version: Windows 7 Ultimate SP1 x64
• Cairo version: 0.4.133.47321 - Pre-release
• 32-bit or 64-bit: 64 Bit
• In Cairo Settings > Advanced, is Cairo set as shell?: No

Additional context

Screenshots