FIX: Windows 95 GDI Leak with Show Window Contents Setting

The information in this article applies to:

• Microsoft Visual FoxPro for Windows, version 3.0

SYMPTOMS

With the Project Manager open, GDI resources dwindle when dragging windows within Visual FoxPro under Windows 95 if the Microsoft Plus feature "Show window contents while dragging" is enabled.

WORKAROUND

The loss of GDI resources can be prevented by disabling the Microsoft Plus "Show window contents while dragging" feature. If the GDI resources become very low, most may be recovered by exiting and then restarting Visual FoxPro.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem was corrected in Visual FoxPro 3.0b for Windows.

MORE INFORMATION

Microsoft Plus is a set of companion enhancements for Windows 95 which can be installed to add functionality to the base feature set of Windows 95.

Steps to Reproduce Problem

1. Install Microsoft Plus, and select the "Visual Enhancements" option when installing.

2. Using the right mouse button, click the Windows 95 desktop, and select Properties.

3. Click the Plus! tab, and select the "Show window contents while dragging" check box. The Plus! tab will not be available if Microsoft Plus is not installed.

4. Start the Windows 95 System Resource Meter from the Start Menu. Click the Start button. Then click Programs, click Accessories, click System Tools, and click Resource Meter. A green icon will appear in the Taskbar to the left of the clock.

   If the Resource Meter does not appear in the Start menu, it has not been installed. Install it by opening the Control Panel under My Computer. Click the Add/Remove Programs icon. Then click the Windows Setup tab, and select Accessories in the Components list. Click Details, and select the System Resource Meter check box in the Components list. Click the OK button twice. Windows 95 will prompt for the CD-ROM disc or floppy disk to complete the installation.

5. Start Visual FoxPro, and create a new project by clicking New on the File menu. Click Project, and then click New File. Type testproj in the Enter box of the Save As dialog box, and click Save.

6. Add a new form to the project by clicking the Documents tab of the Project Manager. Then select Forms, and click New. Click New Form to create the form.

7. Check the current System Resources by placing the mouse pointer over the green System Resource Meter icon in the taskbar. The percentage of available System, User, and GDI resources appears. Note the GDI percentage.

8. Click the Form Designer title bar in the center, hold down the mouse button and drag the mouse pointer around the Visual FoxPro desktop as follows: top right, top left, bottom left, bottom right. Repeat this about 20 times.

9. Repeat step 7, and read the GDI percentage. Observe that it falls by from 1% to 5% for each set of 20 drags of the form designer around the Visual FoxPro desktop.

Additional Notes

• The GDI does not leak memory if the Project Manager is not open or if "Show window contents while dragging" is not enabled.
• Closing all windows in Visual FoxPro will not fully recover the GDI resources lost. Closing Visual FoxPro itself will cause most or all of the GDI resources to be recovered.
• During a long programming session, the GDI resources will eventually become depleted. At this point, you need to exit Visual FoxPro and restart to recover the resources.