I debated whether to open a new search style issue and copy a message or defer ttk for config to another issue and re-title this.  I went with widget group rather than aspect (style) this time. There are multiple search behavior issues.

I added Notepad, Workpad, Libre Office Write, Tortoise Hg, and browsers to Notepad++ for Find/Search and Replace dialog box comparisons.  From top to bottom.

0.1 De-modalize: The others are not modal and it is a nuisance.  #24760 is about same for Config dialog. #24813 for Help stuff.  I should look at your patches now.

0.2 List under Windows menu so easier to bring to top to use or close.  Currently, cannot access Windows menu or anything else do to modality.  Fortunately, Windows does list on popup expansion of taskbar icon.

1.0 Title: delete obvious "Dialog", add file base name.  I sometime forget which file Search box is attached to and waste time searching wrong file.  Will get worse with multiple boxes.

1.1 With tk, can we delete [-] min and [[]] max buttons and leave [X] close button?  They are not present for 4 apps with floating boxes.  #24039 is about inconsistent behavior of these buttons.  If deleting them is a possible solution, I want to consider it.

2. I do not see 'whitespace around gray widgets', but I don't think I need to.  I do see widgets jammed against edges and agree space is needed.  Framing will also be wanted, I expect, as a pane for future single big window version of IDLE.

I just noticed that TortoiseHg has 4 options for its main pane, Search being one of them.  The 'tabs' are icons in a vertical strip to the right.  Search is a magnifying glass.  Each has a mouse hover popup word.

3. Regular expression, Match case, and Whole word modify What to search for, and belong together.  Wraparound, Up, and Down modify How to search, and I think also belong together on a line.  Grid would be 4 columns for these.

4.1 Close button should be at bottom or to the right. L.O.Write has [Help] and [Close] to bottom left and right respectively.  I want to consider this.  We could add a new parameter 'start_at' to help.py classes, defaulting to the top.  "if start_at: <simulate TOC click>"  Then [Help] would display a new section "Search and Replace" added to the idle.rst and hence help.html.  'Find' is non-overlapping.  'Relational expression' uses patterns as defined in re doc.  I have found 'whole word' not as obvious as I expected.  It should have an explicit definition and behavior to match. Ditto for 'Match case' in a unicode world.

4.2  Putting the 4 F & R buttons across the bottom on platforms where that is the norm is OK with me.  I only see down the side so far on Windows.  Search could (should?) have [Find all] in addition to [Find next].  The 4 F & R buttons could be Find, Find all, Replace, Replace all (L.O.Write).  But behavior change should be different issue.