diff --git a/include/config.h b/include/config.h
index 6ab6baee..986f7aa2 100644
--- a/include/config.h
+++ b/include/config.h
@@ -127,6 +127,12 @@ struct Config {
                 struct Colortriple unfocused;
                 struct Colortriple urgent;
         } bar;
+
+        /** What should happen when a new popup is opened during fullscreen mode */
+        enum {
+                PDF_LEAVE_FULLSCREEN = 0,
+                PDF_IGNORE = 1
+        } popup_during_fullscreen;
 };
 
 /**
diff --git a/src/cfgparse.l b/src/cfgparse.l
index 66afb14b..b8b1d73d 100644
--- a/src/cfgparse.l
+++ b/src/cfgparse.l
@@ -99,6 +99,9 @@ none                            { return TOK_NONE; }
 1pixel                          { return TOK_1PIXEL; }
 focus_follows_mouse             { return TOKFOCUSFOLLOWSMOUSE; }
 workspace_bar                   { return TOKWORKSPACEBAR; }
+popup_during_fullscreen         { return TOK_POPUP_DURING_FULLSCREEN; }
+ignore                          { return TOK_IGNORE; }
+leave_fullscreen                { return TOK_LEAVE_FULLSCREEN; }
 default                         { /* yylval.number = MODE_DEFAULT; */return TOKCONTAINERMODE; }
 stacking                        { /* yylval.number = MODE_STACK; */return TOKCONTAINERMODE; }
 tabbed                          { /* yylval.number = MODE_TABBED; */return TOKCONTAINERMODE; }
diff --git a/src/cfgparse.y b/src/cfgparse.y
index d3a5ecda..adb02122 100644
--- a/src/cfgparse.y
+++ b/src/cfgparse.y
@@ -233,6 +233,9 @@ void parse_file(const char *f) {
 %token TOKWORKSPACEBAR "workspace_bar"
 %token TOKCONTAINERMODE "default/stacking/tabbed"
 %token TOKSTACKLIMIT "stack-limit"
+%token TOK_POPUP_DURING_FULLSCREEN "popup_during_fullscreen"
+%token TOK_IGNORE "ignore"
+%token TOK_LEAVE_FULLSCREEN "leave_fullscreen"
 
 %%
 
@@ -260,6 +263,7 @@ line:
         | terminal
         | font
         | comment
+        | popup_during_fullscreen
         ;
 
 comment:
@@ -641,3 +645,16 @@ binding_modifier:
         | TOKCONTROL    { $<number>$ = BIND_CONTROL; }
         | TOKSHIFT      { $<number>$ = BIND_SHIFT; }
         ;
+
+popup_during_fullscreen:
+        TOK_POPUP_DURING_FULLSCREEN WHITESPACE popup_setting
+        {
+                DLOG("popup_during_fullscreen setting: %d\n", $<number>3);
+                config.popup_during_fullscreen = $<number>3;
+        }
+        ;
+
+popup_setting:
+        TOK_IGNORE              { $<number>$ = PDF_IGNORE; }
+        | TOK_LEAVE_FULLSCREEN  { $<number>$ = PDF_LEAVE_FULLSCREEN; }
+        ;
diff --git a/src/manage.c b/src/manage.c
index cd82d020..53526f6a 100644
--- a/src/manage.c
+++ b/src/manage.c
@@ -247,9 +247,20 @@ void manage_window(xcb_window_t window, xcb_get_window_attributes_cookie_t cooki
     if (cwindow->transient_for != XCB_NONE ||
         (cwindow->leader != XCB_NONE &&
          cwindow->leader != cwindow->id &&
-         con_by_window_id(cwindow->leader) != NULL))
+         con_by_window_id(cwindow->leader) != NULL)) {
+        LOG("This window is transiert for another window, setting floating\n");
         want_floating = true;
 
+        if (config.popup_during_fullscreen == PDF_LEAVE_FULLSCREEN) {
+            Con *ws = con_get_workspace(nc);
+            Con *fs = con_get_fullscreen_con(ws);
+            if (fs != NULL) {
+                LOG("There is a fullscreen window, leaving fullscreen mode\n");
+                con_toggle_fullscreen(fs);
+            }
+        }
+    }
+
     /* dock clients cannot be floating, that makes no sense */
     if (cwindow->dock)
         want_floating = false;