diff --git a/src/app.c b/src/app.c

index 2f4b4fb8..2bad3cb6 100644

--- a/src/app.c

+++ b/src/app.c

@@ -425,12 +425,22 @@ static iBool loadState_App_(iApp *d) {

                 readf_Stream(stream_File(f)),

                 readf_Stream(stream_File(f))

             };

+ iIntSet *closedFolders[2] = {

+ collectNew_IntSet(),

+ collectNew_IntSet()

+ };

+ if (version >= bookmarkFolderState_FileVersion) {

+ deserialize_IntSet(closedFolders[0], stream_File(f));

+ deserialize_IntSet(closedFolders[1], stream_File(f));

+ }

             const uint8_t rootIndex = bits & 0xff;

             const uint8_t flags     = bits >> 8;

             iRoot *root = d->window->base.roots[rootIndex];

             if (root) {

                 iSidebarWidget *sidebar  = findChild_Widget(root->widget, "sidebar");

                 iSidebarWidget *sidebar2 = findChild_Widget(root->widget, "sidebar2");

+ setClosedFolders_SidebarWidget(sidebar, closedFolders[0]);

+ setClosedFolders_SidebarWidget(sidebar2, closedFolders[1]);

                 postCommandf_Root(root, "sidebar.mode arg:%u", modes & 0xf);

                 postCommandf_Root(root, "sidebar2.mode arg:%u", modes >> 4);

                 if (deviceType_App() != phone_AppDeviceType) {

@@ -513,6 +523,8 @@ static void saveState_App_(const iApp *d) {

                              (mode_SidebarWidget(sidebar2) << 4));

                 writef_Stream(stream_File(f), width_SidebarWidget(sidebar));

                 writef_Stream(stream_File(f), width_SidebarWidget(sidebar2));

+ serialize_IntSet(closedFolders_SidebarWidget(sidebar), stream_File(f));

+ serialize_IntSet(closedFolders_SidebarWidget(sidebar2), stream_File(f));

             }

         }

     }

diff --git a/src/defs.h b/src/defs.h

index a81d57f1..e1c0a125 100644

--- a/src/defs.h

+++ b/src/defs.h

@@ -36,9 +36,10 @@ enum iFileVersion {

 multipleRoots_FileVersion           = 2,

 serializedSidebarState_FileVersion  = 3,

 addedRecentUrlFlags_FileVersion     = 4,

+ bookmarkFolderState_FileVersion = 5,

 /* meta */

 idents_FileVersion = 1, /* version used by GmCerts/idents.lgr */

- latest_FileVersion = 4,

+ latest_FileVersion = 5,

};



enum iImageStyle {

diff --git a/src/ui/sidebarwidget.c b/src/ui/sidebarwidget.c

index 8e38dcb8..3018f16d 100644

--- a/src/ui/sidebarwidget.c

+++ b/src/ui/sidebarwidget.c

@@ -108,7 +108,7 @@ struct Impl_SidebarWidget {

 iWidget *         menu;

 iSidebarItem *    contextItem;  /* list item accessed in the context menu */

 size_t            contextIndex; /* index of list item accessed in the context menu */

- iIntSet closedFolders; /* otherwise open */

+ iIntSet * closedFolders; /* otherwise open */

};



iDefineObjectConstructionArgs(SidebarWidget, (enum iSidebarSide side), side)

@@ -255,7 +255,7 @@ static void updateContextMenu_SidebarWidget_(iSidebarWidget *d) {



static iBool isBookmarkFolded_SidebarWidget_(const iSidebarWidget *d, const iBookmark *bm) {

 while (bm->parentId) {

- if (contains_IntSet(&d->closedFolders, bm->parentId)) {

+ if (contains_IntSet(d->closedFolders, bm->parentId)) {

         return iTrue;

     }

     bm = get_Bookmarks(bookmarks_App(), bm->parentId);

@@ -397,7 +397,7 @@ static void updateItems_SidebarWidget_(iSidebarWidget *d) {

             item->id = id_Bookmark(bm);

             item->indent = depth_Bookmark(bm);

             if (isFolder_Bookmark(bm)) {

- item->icon = contains_IntSet(&d->closedFolders, item->id) ? 0x27e9 : 0xfe40;

+ item->icon = contains_IntSet(d->closedFolders, item->id) ? 0x27e9 : 0xfe40;

             }

             else {

                 item->icon = bm->icon;

@@ -655,6 +655,11 @@ iBool setMode_SidebarWidget(iSidebarWidget *d, enum iSidebarMode mode) {

 return iTrue;

}



+void setClosedFolders_SidebarWidget(iSidebarWidget *d, const iIntSet *closedFolders) {

+ delete_IntSet(d->closedFolders);

+ d->closedFolders = copy_IntSet(closedFolders);

+}

+

enum iSidebarMode mode_SidebarWidget(const iSidebarWidget *d) {

 return d ? d->mode : 0;

}

@@ -663,6 +668,10 @@ float width_SidebarWidget(const iSidebarWidget *d) {

 return d ? d->widthAsGaps : 0;

}



+const iIntSet *closedFolders_SidebarWidget(const iSidebarWidget *d) {

+ return d->closedFolders;

+}

+

static const char *normalModeLabels_[max_SidebarMode] = {

 book_Icon   " ${sidebar.bookmarks}",

 star_Icon   " ${sidebar.feeds}",

@@ -736,7 +745,7 @@ void init_SidebarWidget(iSidebarWidget *d, enum iSidebarSide side) {

 d->resizer = NULL;

 d->list = NULL;

 d->actions = NULL;

- init_IntSet(&d->closedFolders);

+ d->closedFolders = new_IntSet();

 /* On a phone, the right sidebar is used exclusively for Identities. */

 const iBool isPhone = deviceType_App() == phone_AppDeviceType;

 if (!isPhone || d->side == left_SidebarSide) {

@@ -820,7 +829,7 @@ void init_SidebarWidget(iSidebarWidget *d, enum iSidebarSide side) {



void deinit_SidebarWidget(iSidebarWidget *d) {

 deinit_String(&d->cmdPrefix);

- deinit_IntSet(&d->closedFolders);

+ delete_IntSet(d->closedFolders);

}



iBool setButtonFont_SidebarWidget(iSidebarWidget *d, int font) {

@@ -869,11 +878,11 @@ static void itemClicked_SidebarWidget_(iSidebarWidget *d, iSidebarItem *item, si

     }

     case bookmarks_SidebarMode:

         if (isEmpty_String(&item->url)) /* a folder */ {

- if (contains_IntSet(&d->closedFolders, item->id)) {

- remove_IntSet(&d->closedFolders, item->id);

+ if (contains_IntSet(d->closedFolders, item->id)) {

+ remove_IntSet(d->closedFolders, item->id);

             }

             else {

- insert_IntSet(&d->closedFolders, item->id);

+ insert_IntSet(d->closedFolders, item->id);

             }

             updateItems_SidebarWidget_(d);

             break;

@@ -956,8 +965,8 @@ void setWidth_SidebarWidget(iSidebarWidget *d, float widthAsGaps) {

 int width = widthAsGaps * gap_UI; /* in pixels */

 if (!isFixedWidth) {

     /* Even less space if the other sidebar is visible, too. */

- const int otherWidth =

- width_Widget(findWidget_App(d->side == left_SidebarSide ? "sidebar2" : "sidebar"));

+ const iWidget *other = findWidget_App(d->side == left_SidebarSide ? "sidebar2" : "sidebar");

+ const int otherWidth = isVisible_Widget(other) ? width_Widget(other) : 0;

     width = iClamp(width, 30 * gap_UI, size_Root(w->root).x - 50 * gap_UI - otherWidth);

 }

 d->widthAsGaps = (float) width / (float) gap_UI;

@@ -1328,6 +1337,8 @@ static iBool processEvent_SidebarWidget_(iSidebarWidget *d, const SDL_Event *ev)

             if (isFolder_Bookmark(bm)) {

                 const iPtrArray *list = list_Bookmarks(bookmarks_App(), NULL,

                                                        filterInsideFolder_Bookmark, bm);

+ /* Folder deletion requires confirmation because folders can contain

+ any number of bookmarks and other folders. */

                 if (argLabel_Command(cmd, "confirmed") || isEmpty_PtrArray(list)) {

                     iConstForEach(PtrArray, i, list) {

                         removeEntries_Feeds(id_Bookmark(i.ptr));

diff --git a/src/ui/sidebarwidget.h b/src/ui/sidebarwidget.h

index 2894a951..638a1f2f 100644

--- a/src/ui/sidebarwidget.h

+++ b/src/ui/sidebarwidget.h

@@ -24,6 +24,8 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */



#include "widget.h"



+#include <the_Foundation/intset.h>

+

enum iSidebarMode {

 bookmarks_SidebarMode,

 feeds_SidebarMode,

@@ -49,8 +51,10 @@ iDeclareWidgetClass(SidebarWidget)

iDeclareObjectConstructionArgs(SidebarWidget, enum iSidebarSide side)



iBool setMode_SidebarWidget (iSidebarWidget *, enum iSidebarMode mode);

+void setWidth_SidebarWidget (iSidebarWidget *, float widthAsGaps);

iBool setButtonFont_SidebarWidget (iSidebarWidget *, int font);

+void setClosedFolders_SidebarWidget (iSidebarWidget *, const iIntSet *closedFolders);



enum iSidebarMode mode_SidebarWidget (const iSidebarWidget *);

float width_SidebarWidget (const iSidebarWidget *);

-void setWidth_SidebarWidget (iSidebarWidget *, float widthAsGaps);

+const iIntSet * closedFolders_SidebarWidget (const iSidebarWidget *);

diff --git a/src/ui/window.c b/src/ui/window.c

index 5941ef5f..066ea102 100644

--- a/src/ui/window.c

+++ b/src/ui/window.c

@@ -30,6 +30,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */

#include "keys.h"

#include "labelwidget.h"

#include "documentwidget.h"

+#include "sidebarwidget.h"

#include "paint.h"

#include "root.h"

#include "touch.h"

@@ -1421,6 +1422,15 @@ void setSplitMode_MainWindow(iMainWindow *d, int splitFlags) {

         w->keyRoot->window     = w;

         setCurrent_Root(w->roots[newRootIndex]);

         createUserInterface_Root(w->roots[newRootIndex]);

+ /* Bookmark folder state will match the old root's state. */ {

+ for (int sb = 0; sb < 2; sb++) {

+ const char *sbId = (sb == 0 ? "sidebar" : "sidebar2");

+ setClosedFolders_SidebarWidget(

+ findChild_Widget(w->roots[newRootIndex]->widget, sbId),

+ closedFolders_SidebarWidget(

+ findChild_Widget(w->roots[newRootIndex ^ 1]->widget, sbId)));

+ }

+ }

         if (!isEmpty_String(d->pendingSplitUrl)) {

             postCommandf_Root(w->roots[newRootIndex], "open url:%s",

                               cstr_String(d->pendingSplitUrl));