Description:
Using Calc a command button placed on the spreadsheet begins to judder as soon as I use the scroll bar. When the juddering starts, using the mouse or keyboard becomes seriously delayed as if the juddering command button is taking up all the processor time.

Steps to Reproduce:
1.Place command button on spreadsheet and attach macro.
2.Save and close spreadsheet. Reload spreadsheet
3.Use scrollbar to pan right and the command button will begin to judder.

Actual Results:
Command button begins to judder and spreadsheet performance becomes sluggish as if processor power is dominated by button judder

Expected Results:
spreadsheet should behave normally but it doesn't


Reproducible: Always


User Profile Reset: No


OpenGL enabled: Yes

Additional Info:
Version: 6.3.3.2 (x64)
Build ID: a64200df03143b798afd1ec74a12ab50359878ed
CPU threads: 8; OS: Windows 6.1; UI render: default; VCL: win; 
Locale: en-GB (en_GB); UI-Language: en-US
Calc: threaded