Hello guys
Update: 25th April 2019
It looks like, setting up the compatibility for Windows 7 solves the Reports Builder shaking, freezing behavior to a greater extend. Going on with the “Fix” as NOTHING else could be done with a product that is NOT anymore supported by Oracle.
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I “trust” Microsoft and I do update my Work/Home/VMs regularly. Ahum! 99.9% of the times I never had to go back and fix anything, that .1% times, things went awfully bad.
I cannot confirm which update, certainly one update within last 2 months have made Oracle Reports Developer 10g/6i loads messier than earlier. Now both version of reports developer will NOT load the layout designer properly.

The interesting factor about the layout designer is:
It hangs more often when you have multiple reports opened from a single instance of the reports developer & you are switching between the layouts.
For example, if you opened Report 1’s layout & closed it, then opening the Report 2’s layout arrests the designer & all the toolbar icons and rest go astray (as you could see with above image) which will force you to end task the developer using Task Manager/or other known measures.
It is irky, shaky, yet you can do your work with multiple sessions of reports developer opened with only one report loaded. There are no guarantees that this IS the ultimate solution. I often have to terminate the report builder and restart it to do my development(s) :(
I’ve more news for you. I did a reinstall routine of Patch 3 for 10g developer & remembering Windows 7 was the last OS certified with the developer suite, changed the compatibility for the Report Developer and set it as Windows 7. I am not sure whether it acts as a mediator, my report builder is much stable as I am jolting these few lines. Keeping fingers crossed.
regards,