src/vs/workbench/browser/layout.ts/Layout/resizePart
class Layout:	resizePart(part: Parts, sizeChangeWidth: number, sizeChangeHeight: number): void {
		const sizeChangePxWidth = Math.sign(sizeChangeWidth) * computeScreenAwareSize(Math.abs(sizeChangeWidth));
		const sizeChangePxHeight = Math.sign(sizeChangeHeight) * computeScreenAwareSize(Math.abs(sizeChangeHeight));

		let viewSize: IViewSize;

		switch (part) {
			case Parts.SIDEBAR_PART:
				viewSize = this.workbenchGrid.getViewSize(this.sideBarPartView);
				this.workbenchGrid.resizeView(this.sideBarPartView,
					{
						width: viewSize.width + sizeChangePxWidth,
						height: viewSize.height
					});

				break;
			case Parts.PANEL_PART:
				viewSize = this.workbenchGrid.getViewSize(this.panelPartView);

				this.workbenchGrid.resizeView(this.panelPartView,
					{
						width: viewSize.width + (this.getPanelPosition() !== Position.BOTTOM ? sizeChangePxWidth : 0),
						height: viewSize.height + (this.getPanelPosition() !== Position.BOTTOM ? 0 : sizeChangePxHeight)
					});

				break;
			case Parts.AUXILIARYBAR_PART:
				viewSize = this.workbenchGrid.getViewSize(this.auxiliaryBarPartView);
				this.workbenchGrid.resizeView(this.auxiliaryBarPartView,
					{
						width: viewSize.width + sizeChangePxWidth,
						height: viewSize.height
					});
				break;
			case Parts.EDITOR_PART:
				viewSize = this.workbenchGrid.getViewSize(this.editorPartView);

				// Single Editor Group
				if (this.editorGroupService.count === 1) {
					this.workbenchGrid.resizeView(this.editorPartView,
						{
							width: viewSize.width + sizeChangePxWidth,
							height: viewSize.height + sizeChangePxHeight
						});
				} else {
					const activeGroup = this.editorGroupService.activeGroup;

					const { width, height } = this.editorGroupService.getSize(activeGroup);
					this.editorGroupService.setSize(activeGroup, { width: width + sizeChangePxWidth, height: height + sizeChangePxHeight });

					// After resizing the editor group
					// if it does not change in either direction
					// try resizing the full editor part
					const { width: newWidth, height: newHeight } = this.editorGroupService.getSize(activeGroup);
					if ((sizeChangePxHeight && height === newHeight) || (sizeChangePxWidth && width === newWidth)) {
						this.workbenchGrid.resizeView(this.editorPartView,
							{
								width: viewSize.width + (sizeChangePxWidth && width === newWidth ? sizeChangePxWidth : 0),
								height: viewSize.height + (sizeChangePxHeight && height === newHeight ? sizeChangePxHeight : 0)
							});
					}
				}

				break;
			default:
				return; // Cannot resize other parts
		}
	}