Description of the Issue

When I click on the last tab in my tab bar when it's partially visible in the bar, the tab is 'picked up' as if dragging and dropping, and it does not release until I click somehwere

Steps to Reproduce the Issue

1. Open enough tabs that you must scroll to see all of them. (or resize your window smaller than the length of the tab bar)
2. Scroll to where the last tab is partially visible. ( the filename may need to be long enough for this to happen)
3. Click the last tab while partially visible, and it acts like you're dragging the tab.

Expected Behavior

When the tab is clicked, it shows the document and the tab does not get dragged.

Actual Behavior

The tab acts as if it is being dragged despite not holding down the left mouse button.

Debug Information

Notepad++ v7.5.1 (32-bit)
Build time : Aug 29 2017 - 02:35:41
Path : C:\Users<redacted>\Documents\Notepad++\notepad++.exe
Admin mode : OFF
Local Conf mode : OFF
OS : Windows 7 (64-bit)
Plugins : none