How to reproduce:
1. Open the “timeline_window_bug.zip“ project
2. Open the “SampleScene”
3. Open the Timeline window (Window > Sequencing > Timeline)
4. Select the “timeline“ GameObject in the Hierarchy
5. Maximize and un-maximize the Timeline window
6. Observe the Timeline window

Expected results: The Timeline window remembers the selected GameObject
Actual results: The Timeline window forgets the selected GameObject and requires it to be selected again

Reproducible in: 1.6.5, 1.7.6, 1.8.6 (2021.3.37f1, 2022.3.25f1, 2023.2.19f1, 6000.0.0b16)

Reproduced on: Windows 11 Pro (23H2), macOS 14.4 (by the reporter)
Not reproduced on: No other environment tested

Notes:
- The issue is not reproducible in the Timeline window when it is not docked on the Editor (if it is a floating window)
- The issue does not reproduce on the Animation window
- This issue reproduces even when the GameObject remains selected, in that case, another GameObject has to be selected, and the first one reselected