DocumentsMainImpl.toEditorOpenerOptions should convert ViewColumn to zero-based index

[godlin-gh]

Description

when i call plugin api window.showTextDocument, the call hierarchy looks like:
DocumentsMainImpl.$tryShowDocument -> DocumentsMainImpl.toEditorOpenerOptions

theia/packages/plugin-ext/src/main/browser/documents-main.ts

Lines 176 to 188 in a99b585

	async $tryShowDocument(uri: UriComponents, options?: TextDocumentShowOptions): Promise<void> {
	// Removing try-catch block here makes it not possible to handle errors.
	// Following message is appeared in browser console
	// - Uncaught (in promise) Error: Cannot read property 'message' of undefined.
	try {
	const editorOptions = DocumentsMainImpl.toEditorOpenerOptions(this.shell, options);
	const uriArg = new URI(CodeURI.revive(uri));
	const opener = await this.openerService.getOpener(uriArg, editorOptions);
	await opener.open(uriArg, editorOptions);
	} catch (err) {
	throw new Error(err);
	}
	}

theia/packages/plugin-ext/src/main/browser/documents-main.ts

Lines 240 to 246 in a99b585

	} else if (viewColumn > 0) {
	const tabBars = shell.mainAreaTabBars;
	const tabBar = tabBars[viewColumn];
	if (tabBar && tabBar.currentTitle) {
	widgetOptions = { ref: tabBar.currentTitle.owner };
	}
	}

the ViewColumn type use one-based index which should be convert to zero-based index inside toEditorOpenerOptions method

Reproduction Steps

try to call window.showTextDocument(xx, { viewColumn: ViewColumn.One }), you can never open an editor on first column.

OS and Theia version:
master
Diagnostics:

[godlin-gh]

I found there are two other reference of toEditorOpenerOptions method at plugin-vscode-commands-contribution.ts

one of that convert the viewColumn to zero-based index using fromViewColumn method outside toEditorOpenerOptions like below:

theia/packages/plugin-ext-vscode/src/browser/plugin-vscode-commands-contribution.ts

Lines 78 to 103 in a99b585

	registerCommands(commands: CommandRegistry): void {
	commands.registerCommand(VscodeCommands.OPEN, {
	isVisible: () => false,
	execute: async (resource: URI, columnOrOptions?: ViewColumn | TextDocumentShowOptions) => {
	if (!resource) {
	throw new Error(`${VscodeCommands.OPEN.id} command requires at least URI argument.`);
	}
	if (!URI.isUri(resource)) {
	throw new Error(`Invalid argument for ${VscodeCommands.OPEN.id} command with URI argument. Found ${resource}`);
	}
	let options: TextDocumentShowOptions | undefined;
	if (typeof columnOrOptions === 'number') {
	options = {
	viewColumn: fromViewColumn(columnOrOptions)
	};
	} else if (columnOrOptions) {
	options = {
	...columnOrOptions,
	viewColumn: fromViewColumn(columnOrOptions.viewColumn)
	};
	}
	const editorOptions = DocumentsMainImpl.toEditorOpenerOptions(this.shell, options);
	await open(this.openerService, new TheiaURI(resource), editorOptions);
	}
	});

I think assigning 0 value to a viewColumn may be confused, we shoud do that inside the toEditorOpenerOptions instead and make sure it works on other place.

[akosyakov]

@godlin-gh it sounds reasonable, feel free to work on it.