Description of problem:
In most cases, when I expand or collapse an item in the Commits field 9part of the VCS exntension), the item gets displayed in the configured 'selection' colour, as if I had dragged the mouse over the text to select it.

Further, the previously visible part of the text ends up in my X11 clipboard, and can be pasted elsewhere with the middle mouse button.  If I was expanding the item, the collapsed version of the text ends up in my clipboard, and if I was collapsing the item, the expanded text ends up in my clipboard.

Version-Release number of selected component (if applicable):
4.4.4021

How reproducible:
90%

Steps to Reproduce:
1. Open a bug that has at least two items in the Commits field.
2. Click the + icon beside the first commit.
3. Observe that the commit is painted with the highlight/selection colour after expanding.
4. Middle-click in a widget that can accept text.
5. Observe that the first line of the commit clicked in step 2 is pasted.
6. Click the - icon beside the first commit.
7. Observe that the commit is painted with the highlight/selection colour after collapsing.
8. Middle-lcick in a widget that can accept text. 
9. Observe that the full text of the commit clicked in step 6 is pasted.
10. Click the + icon beside the second commit.
11. Observe that the second commit is painted with the highlight/selection colour after expanding.

Actual results:
Last commit collapsed or expanded has the selection colour. Text of commit enters clipboard.

Expected results:
Last commit collapsed or expanded has nornal text colour. Clipboard contents are unchanged.

Additional info:
Tested on Fedora 20 and Firefox 30.0.