How to stop OpenOffice/LibreOffice from popping up toolbars when I click on stuff

Not exactly the desired result, but OpenOffice will remember if such a floating toolbar was deselected using "View" -> "Toolbars" (found this in an OOo forum - credits: this post).

For example: OOo will show the "table" toolbar if the cursor is inside a table. If the table toolbar is visible, you can hide it using "View" -> "Toolbars" and deselect "Table". OOo will take account of it and won't show the table toolbar automatically furthermore. Using the toolbar's context menu won't work this way - it will hide the toolbar only once and display it again the next time.

I prevented the screen from moving around by dragging the toolbar so that it becomes floating.

I worked around this annoying issue by placing a small toolbar that doesn't hide on a second line below the default-toolbar. When the evasive toolbar shows, put it next to the small one on the same line. It will still flicker in and out, but it wont cause your whole working area to jump around.