Textarea in Webview loses caret/focus indication

[kieferrm]

Issue Type: Bug

I encounter this regularly on Windows when using the GH PR extension.

1. Open a text editor
2. Open a PR overview page
3. Set the cursor to leave a comment (this usually shows the caret)
4. Switch to the text editor
5. Switch back to the PR overview page
6. Set the cursor to leave a comment
   -> No caret, the text insert position however is tracked correctly

VS Code version: Code - Insiders 1.31.0-insider (ed5363e, 2019-01-02T17:25:53.371Z)
OS version: Windows_NT x64 10.0.17763

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz (4 x 2808)
GPU Status	2d_canvas: enabled checker_imaging: disabled_off flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: disabled_software rasterization: enabled surface_synchronization: enabled_on video_decode: enabled webgl: enabled webgl2: enabled
Memory (System)	15.93GB (6.46GB free)
Process Argv
Screen Reader	no
VM	0%

Extensions (21)

Extension	Author (truncated)	Version
markdown-preview-github-styles	bie	0.1.4
solargraph	cas	0.19.1
regex	chr	0.2.0
gitlens	eam	9.3.0
remotehub	eam	0.2.0
tslint	eg2	1.0.42
vsc-material-theme	Equ	2.6.3
vscode-pull-request-github	Git	0.3.2
mdmath	goe	2.3.7
svgpreview	kis	0.2.0
vscode-azurestorage	ms-	0.5.0
mssql	ms-	1.4.0
python	ms-	2018.12.1
azure-account	ms-	0.8.0
azurecli	ms-	0.4.2
Go	ms-	0.8.0
vscode-docker	Pet	0.4.0
material-icon-theme	PKi	3.6.2
ruby	reb	0.21.0
notification-tester	svi	2.0.4
vscode-open-in-github	ziy	1.3.6

(2 theme extensions excluded)

[mjbvz]

#48604 tracks restoring focus. The PR extension does not use retainContextWhileHidden but they could implement a custom solution using webview state. For webviews that use retainContextWhileHidden , VS Code could track which element is focused and restore the focus to it

The focus not being visually indicated is tracked by #65410. Will see if we can workaround this for VS Code 1.31