Currently 'activate_init' layout property doesn't work for popups which run their draw function multiple times once opened.
Operating system: Linux-5.3.7-arch1-1-ARCH-x86_64-with-arch 64 Bits
Graphics card: GeForce GTX 660M/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 435.21
2.81 (sub 15), branch: master, commit date: 2019-10-24 19:00, hash: rB892c3891ed0b
2.82 (sub 1), branch: master, commit date: 2019-10-24 19:11, hash: rB2a3b5dc73038
Short description of error
Setting the activate_init property of a UILayout causes weird behavior and often causes the blender ui to freeze. I'm including a test addon that utilizes activate_init in a panel, a popup, and an item within a UIList in a popup. Both the popup and the UIList item cause the whole ui to freeze after interacting with them, while the panel just isn't affected at all. The weird behavior only seems to happen after you press enter or otherwise finish interacting with the auto-activated field; everything acts like you would expect until you finish and find the UI is non-responsive.
The panel is named Test Panel and located in the Object tab of the Properties Editor.
The popup can be called by pressing ALT-T
The UIList can be called by pressing CTRL-T
Exact steps for others to reproduce the error
Install and activate the test addon.
Press one of the hotkeys.
Press enter to finish editing the auto activated field.
Try to pan the 3D View using the middle mouse button.