Created attachment 161415 [details]
Simple example ODS file containing a large sized chart

While editing a chart, the sidebar changes to a single deck - Properties.  If the user changes the size of the sidebar and has it covering part of the chart being edited, there will be all kinds of weird display issues.

This may be related to bug 119370, but in my case the sidebar (at least the part without display glitches) still works, so I'm filing separately.

Steps to reproduce:
1. Open the attached example file, reduce the LO window size or expand the chart size if necessary, so that the right edge of the chart is close enough to the separator between spreadsheet area and sidebar;
2. Double-click the chart, going into "edit chart" mode, click on the chart again, so that the edit focus is on the chart part of the OLE object;
3. Now the sidebar should have only one Propeties deck, use mouse to drag the separater left to increase the size of the sidebar, and make it overlapping with the chart;
4. Move mouse around the left (newly expanded) part of the sidebar, or move the mouse back over a cell in the spreadsheet and scroll, and observe all kinds of displaying glitches.

LibreOffice version information:
Version: 6.4.4.2 (x64)
Build ID: 3d775be2011f3886db32dfd395a6a6d1ca2630ff
CPU threads: 2; OS: Windows 10.0 Build 18363; UI render: default; VCL: win; 
Locale: zh-CN (zh_CN); UI-Language: en-US
Calc: threaded

Also reproduced with 7.0.0 beta1.