SourceTree's history view has a log view in the top half and a commit view and a file view in the bottom half. The vertical dividing line between the commit details view and the file details view can be easily moved by clicking and dragging. However, the horizontal dividing line between the log view on the upper half and the two views on the bottom half cannot be moved in some situations.

When the SourceTree window is maximized and a file is selected in the commit view (and therefore shows up in the file view), you can try to click and drag the central horizontal dividing line but it won't move. It seems to be impossible in most cases to deselect a file, but it can be done if "Uncommitted changes" is the selected commit and you stage or unstage a file. Once the file is deselected you can resize the bottom panel. Then once you select another commit and a file automatically becomes selected then some more strange behavior can be observed.

After the central horizontal dividing line has been moved with no files selected, then you can move it when a file is selected but it only moves down to a certain limit. It moves as though there's a limit to how small the bottom panel can get. If you drag past that limit then the panel snaps back to the size it was before you started resizing.

Repro steps:

1. Open a repo with many commits and at least one uncommitted change in SourceTree
2. In the log view in the upper half, select a commit
3. Try to move the central horizontal dividing line between the upper half and the lower half
4. Observe faulty behavior #1 (the line will not move)
5. In the log view in the upper half, select "Uncommitted changes"
6. If a file is selected, stage or unstage it to deselect it
7. Click and drag the central horizontal dividing line between the upper half and the lower half upwards so that the bottom panel becomes large
8. Select a commit
9. Try to move the central horizontal dividing line between the upper half and the lower half downwards so that the bottom panel becomes small
10. Observe faulty behavior #2 (the line will snap back into place when you drag down too far)