Viewer: clamp the drawer divider to the max width too (#85)

The live divider drag only bounded the image view's and drawer's minimum
widths, so in a wide (maximized) window the bar could be dragged far past
the drawer's maximum and then snapped back to it on release. Bound the
image-view width from below by the max-drawer position as well, so the
divider stops cleanly at both the minimum and maximum drawer widths.

Author: chammoru

CHANGELOG.md

@@ -11,7 +11,7 @@ All notable changes to Q1View are documented here. Releases follow [semantic ver
 - Viewer: when the thumbnail drawer has focus, `PgUp`/`PgDn` now step the selection to the previous/next file (matching the main view's file navigation) instead of scrolling by a page — in the gallery grid the page was the whole list, so they had simply duplicated `Home`/`End`. They move the selection only (arrow keys still browse folders; `Enter`/double-click still opens), while `Home`/`End` continue to jump to the first/last item. (issue #84)
 
 ### Fixed
-- Viewer: dragging the thumbnail drawer divider is now a smooth live resize that stops cleanly at the minimum width. It had used the splitter's default XOR "ghost" bar, which was drawn over the thumbnails and flickered, and could overshoot the minimum then snap back on release; the panes now resize in real time, clamped to the minimum, with the menu bar and grid re-fit held until the drag settles. (issue #85)
+- Viewer: dragging the thumbnail drawer divider is now a smooth live resize that stops cleanly at the minimum and maximum widths. It had used the splitter's default XOR "ghost" bar, which was drawn over the thumbnails and flickered, and could overshoot the limit then snap back on release (the overshoot was most obvious past the maximum in a wide/maximized window); the panes now resize in real time, clamped to both bounds, with the menu bar and grid re-fit held until the drag settles. (issue #85)
 - Viewer: resizing the gallery grid with Ctrl+wheel (e.g. from 3 to 2 columns) no longer jolts when the change makes the vertical scrollbar appear or disappear. The grid is now laid out as if the scrollbar is always present, so its width — and therefore the tile size and column count — no longer shifts by a scrollbar's width as the bar toggles.
 - Viewer: opening the thumbnail drawer now scrolls the current image into view, instead of leaving the list at the top.
 - Viewer: the menu bar no longer flickers while the thumbnail drawer slides open or closed. The image refits to the changing view width on every animation frame, and each refit refreshed the magnification readout in the menu with `DrawMenuBar`, repainting the whole (non-buffered) menu bar a dozen times in a fifth of a second. The readout text is still updated during the slide, but the menu is repainted only once, after the slide settles.

Viewer/MainFrm.cpp

@@ -152,8 +152,14 @@ void CDrawerSplitter::OnMouseMove(UINT nFlags, CPoint point)
 		CRect rc;
 		GetClientRect(&rc);
 		int bar = BarWidth();
-		int lo = DRAWER_MIN_IMAGE;                    // image view (col 0) lower bound
-		int hi = rc.Width() - bar - DRAWER_MIN_W;     // so the drawer keeps its minimum
+		// col0 is the image view's width; its bounds keep the drawer within
+		// [DRAWER_MIN_W, DRAWER_MAX_W] and the image view at >= DRAWER_MIN_IMAGE.
+		// Without the max-drawer bound a wide (maximized) window let the divider run
+		// far left and then snap back to the max on release (issue #85).
+		int lo = rc.Width() - bar - DRAWER_MAX_W;     // drawer's maximum width
+		if (lo < DRAWER_MIN_IMAGE)
+			lo = DRAWER_MIN_IMAGE;                    // image view's minimum width
+		int hi = rc.Width() - bar - DRAWER_MIN_W;     // drawer's minimum width
 		if (hi < lo)
 			hi = lo;
 		int col0 = point.x;