To view pdf in same page then please change your browser settings to :
1. Click the menu button Menu and choose Options
2. Select the Applications panel.
3. Find Portable Document Format (PDF) in the list and click on it to select it.
4. Click on the drop-down arrow in the Action column for the above entry and select the PDF viewer (Use Adobe Acrobat in Firefox) you wish to use.
5. Click OK to close the Options window