Occluded windows just went blank

[eamodio]

Issue Type: Bug

I've only seen this once, but it happened to 2 windows at the same time, while I was editing in a 3rd. There was nothing I could do to make it come back other than restart.

/cc @deepak1556

VS Code version: Code - Insiders 1.41.0-insider (f24f483, 2019-11-21T10:43:20.960Z)
OS version: Windows_NT x64 10.0.19028

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz (8 x 4008)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: enabled skia_renderer: disabled_off surface_control: disabled_off surface_synchronization: enabled_on video_decode: enabled viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	31.93GB (17.30GB free)
Process Argv	--enable-proposed-api eamodio.remotehub
Screen Reader	no
VM	0%

[cwadrupldijjit]

It's happened to all open windows. It seems like it continues to work and any running debuggers or console processes are still running. It happened once while I had 6 or 7 windows open at once and all of the windows went blank around the same time. Also just happened now with only 2 windows open right after I started a process in my terminal.

I only noticed this happening after I updated to the latest insiders version.

[eamodio]

It happened again to me, again it was only the background window that it happened to. And when I toggled devtools (via a shortcut key) it fixed the window.

[cwadrupldijjit]

Is there a default hotkey for the devtools or do I need to add that myself?

[eamodio]

I don't think there is one by default, I've have one setup myself.

[JacksonKearl]

I found it happens very consistently when I have a lot of memory pressure, for instance when compiling Code. The window is completely blank, but the pointer will respond to things below (show the select text vs click vs normal glyph), and I can do things like copy text and close the window by clicking where the close button should be.

[deepak1556]

I was able to repro this by just opening windows on top of each other and the occluded window gets blank for every new window opened in FIFO order (starts after 4th window might depend on the memory of your system), which aligns with what @eamodio @cwadrupldijjit are seeing, @JacksonKearl scenario seems different but lets verify once I have a fix for this.

[deepak1556]

I am also able to repro from out of sources with release/1.40 branch, definitely a regression from recent electron version bump

[roblourens]

Maybe #84706 too

[deepak1556]

@roblourens that mac issue is slightly different, I know what might cause that electron/electron#19873, likely electron/electron#21189 but can't confirm a fix for that yet.

[deepak1556]

I have narrowed down the cause,

diff --git a/src/vs/code/electron-main/window.ts b/src/vs/code/electron-main/window.ts
index b55f4095e3..26b10db860 100644
--- a/src/vs/code/electron-main/window.ts
+++ b/src/vs/code/electron-main/window.ts
@@ -132,7 +132,7 @@ export class CodeWindow extends Disposable implements ICodeWindow {
                                        // want to enforce that Code stays in the foreground. This triggers a disable_hidden_
                                        // flag that Electron provides via patch:
                                        // https://github.com/electron/libchromiumcontent/blob/master/patches/common/chromium/disable_hidden.patch
-                                       backgroundThrottling: false,
+                                       // backgroundThrottling: false,
                                        nodeIntegration: true,
                                        nodeIntegrationInWorker: RUN_TEXTMATE_IN_WORKER,
                                        webviewTag: true

reenabling background throttling fixes this. Stems from electron/electron#20239

[deepak1556]

Oh btw you don't have to close or toggle devtools for a temporary fix, anything that triggers a repaint of the window will resolve the issue, so simply minimize and restore the window from task bar. A fix is being actively worked on for the next insiders.

[lediur]

Running into this issue as well. I started working around it by waiting a few seconds, then unminimizing the window by dragging down and shaking it to get it to repaint properly.

[chrmarti]

Fix is in the latest Insiders build (Commit: 599c076, Date: 2019-11-22T07:19:06.796Z).

[wedeluxe]

As I understand, the issue is supposed to be fixed in VS Code 1.40.2.

But actually, upgrading these two packages

code 1.40.1-1 -> 1.40.2-1
electron6 6.1.4-2 -> 6.1.5-1

on my Arch Linux PC introduced this issue.
Never saw that in 1.40.1 and before.

My VS Code session has 10 windows open. 6 out of 10 look blank right after starting VS Code. Blank windows still show tooltips when hovering, so content still exists. As suggested above, triggering a repaint of a blank window (restoring, then maximizing again) is a temporary help. And by the way, unblanking one window blanks another.