"Toggle" commands do not work reliably on Positron view panes

[jmcphers]

This example is with Environment, but reproduces with all of the Positron view panes I tried (including Preview, Plots, etc.)

1. Start Positron; the Environment pane comes up
2. Open the Command Palette and run the View: Toggle Environment command
3. The Environment pane should disappear
4. Run View: Toggle Environment again; nothing happens

In my testing, the commands (very occasionally) did bring the panes into view or hid them, but not reliably; typically once the command has shown and hidden a pane it stops working until you modify the layout using some other command.

[jmcphers]

Wonder if this is related to the issue @softwarenerd and I observed yesterday wherein the panes no longer actually get destroyed when they are off, just hidden. Maybe toggle isn't working because the pane is not able to correctly assess whether it is currently displaying?

[lionel-]

Originally filed in #1475 by @jthomasmock and then in #1488 which is a duplicate of this issue:

The workbench.action.positronConsole.open command stops showing the panel after a few usages.

https://code.visualstudio.com/updates/v1_28#_toggle-panel-changes provides some context on the expected behaviour:

a. Panel shows if not visible.
b. Panel hides if having keyboard focus.
c. Panel gets focused when visible but not focused.

As I stumbled onto this several times as a user of navigation shortcuts, I spent some time to investigate the issue. Here are my notes:

• In a fresh instance of Positron with the console visible and focus on console input, run the command twice. The first time hides the viewpane as expected (behaviour b). The second time shows the console again (behaviour a).

• After that second time, the scroll state is lost. And if you repeat the command again, it will succesfully hide the panel but from then on it will no longer be able to show it back.

• The viewPaneContainer.onDidBlurView() handler doesn't run when the panel is hidden, which prevents the focusedViewContextKey to be reset.

  positron/src/vs/workbench/browser/parts/views/viewsService.ts

  Line 642 in ad5b5fa

  disposables.add(viewPaneContainer.onDidBlurView(view => {

  . The viewpane thinks the console is still selected, and then tries to hide it again instead of showing it (

  positron/src/vs/workbench/browser/parts/views/viewsService.ts

  Line 459 in ad5b5fa

  if (focusedViewId === viewDescriptor.id) {

  ).

• Not only the scroll state was lost when the panel was shown back, the focus state was lost too. I think that is key. If you manually select the console input to force focus, the command is fixed. You can use it to hide the console, and then bring it back. If you use it again without manually focusing the console though, it will break again. I /think/ that because the console doesn't take focus when it's brought back, it also doesn't blur when hidden, which then prevents the viewpane's onblur handler from running.

• The toggling command is supposed to bring focus automatically. For some reason calling this.focus() (this being the PositronConsoleViewPane) doesn't have any effect. I've also noticed that selecting text in the console also doesn't cause the viewpane to focus. Other actions such as single click, or selecting the runtime dropdown menu, do bring focus.

Useful positronConsoleView.tsx printf for debugging:

 		// Create a focus tracker that updates the PositronConsoleFocused context key.
 		const focusTracker = DOM.trackFocus(this.element);
 		this._register(focusTracker);
-		this._register(focusTracker.onDidFocus(() =>
-			this._positronConsoleFocusedContextKey?.set(true)
-		));
-		this._register(focusTracker.onDidBlur(() =>
+		this._register(focusTracker.onDidFocus(() => {
+			console.log("didFocus!");
+			this._positronConsoleFocusedContextKey?.set(true);
+		}));
+		this._register(focusTracker.onDidBlur(() => {
+			console.log("didBlur!");
 			this._positronConsoleFocusedContextKey?.set(false)
-		));
+		}));
 	}
 
 	/**

Could these focus problems be related to the complex behaviour for console scrolling @softwarenerd?

Perhaps also worth noting that an empty ViewPane also suffers from the same (or a similar) problem, so maybe something in the DOM isn't right by default?

[lionel-]

The environment toggling command behaves exactly the same way. If you focus it manually before toggling it off, you can bring it back on with the command.