Per MyDigitalLife, with the following registry trick, you can change or adjust the width or length of the buttons as they appear on the Windows 7 Taskbar, which will have the same effect as modifying the width of the taskbar.
1.Run Registry Editor (RegEdit).
2.Navigate to the following registry key:
3.Right click on a blank space on the right pane, select New, then String Value. Name the new string value as MinWidth.
Note: If “MinWidth” already exists, skip this step.
4.Double click on “MinWidth”, and change the value data according to the preferred size. By default, Windows 7 has the following MinWidth value (estimated), when MinWidth is not defined or not created:
Button with standard or normal icons: 56
Button with small icons: 40
5.Restart the computer, or log off and log on again.
Note: The above change button width trick will only work when Taskbar is set to display “button”, which means it doesn’t work if Taskbar buttons’ behavior is set to “Always combine, hide labels”, where Windows 7 will always use its default size for icon-only button. To change the setting, follow these steps:
1.Right click on Taskbar, and select Properties.
2.Set the Taskbar buttons setting to Never combine (each window has its own icon, and icons span to more rows in Taskbar when there is too many of them), or Combine when taskbar is full (all icons of same application or program will collapse and stack to one when Taskbar no longer able to accommodate additional icon).
To revert and change back to default Taskbar button size of Windows 7, just delete the MinWidth registry value data.