src/vs/editor/browser/controller/mouseTarget.ts/HitTestRequest/_getMouseColumn
class HitTestRequest:	private _getMouseColumn(position: Position | null = null): number {
		if (position && position.column < this._ctx.viewModel.getLineMaxColumn(position.lineNumber)) {
			// Most likely, the line contains foreign decorations...
			return CursorColumns.visibleColumnFromColumn(this._ctx.viewModel.getLineContent(position.lineNumber), position.column, this._ctx.viewModel.model.getOptions().tabSize) + 1;
		}
		return this.mouseColumn;
	}