If you use text boxes to position headings or paragraphs all around the page, you’re clearly outside the target domain of Writer. Writer is intended to manage a flow of paragraphs where they constitute a logical sequence where the topic or subject of a paragraph semantically precedes those of the following.
Writer is built to assign sequential position to paragraph and allocate pages when space is needed. This means pages are not primary objects and have no significance per se.
If page is meaningful and important to you (e.g. your flyer is exactly one page long), you are then in the desktop publishing (DTP) domain, not in the text processing domain. Either use a DTP application like free Scribus or commercial Quark XPress, or as a workaround LO Impress or LO Draw.
Impress (presentation application) formats “slides” and those “slides” can have any size or orientation. However, the body of the slide is still logically sequential by nature.
Draw (graphics application) imposes no structure at all. You allocate pages (any size or orientation) and you position objects anywhere in a page. Objects can be graphic shapes or text boxes. Text inside boxes can be formatted any way you like though it is not as user-friendly as in Writer.
Of course in either case, you won’t be able to save .doc but you won’t experience spurious position changes. If you need to send the result to someone else, export as PDF and this will guarantee fidelity.
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