fix: fix Screenshot fullscreen flickering

kernel/src/Api/WinServer.cpp

@@ -99,7 +99,9 @@ namespace WinServer {
         WindowSlot& slot = g_slots[windowId];
         if (!slot.used || slot.eventMailbox == nullptr) return -1;
 
-        int rc = Ipc::MailboxSend(slot.eventMailbox, 0, event, sizeof(*event));
+        int rc = (event->type == 1)
+            ? Ipc::MailboxSendCoalescedMouse(slot.eventMailbox, 0, event, sizeof(*event))
+            : Ipc::MailboxSend(slot.eventMailbox, 0, event, sizeof(*event));
         return rc > 0 ? 0 : -1;
     }
 

kernel/src/Ipc/Ipc.cpp

@@ -18,6 +18,7 @@
 #include <Timekeeping/ApicTimer.hpp>
 #include <Terminal/Terminal.hpp>
 #include <Api/UserMemory.hpp>
+#include <Api/Syscall.hpp>
 
 namespace Ipc {
 
@@ -851,6 +852,45 @@ namespace Ipc {
         return MailboxSendInternal(mailbox, -1, msgType, data, len, -1);
     }
 
+    int MailboxSendCoalescedMouse(Mailbox* mailbox, uint32_t msgType, const void* data, uint16_t len) {
+        if (mailbox == nullptr || data == nullptr) return -1;
+        if (len != sizeof(Montauk::WinEvent)) return MailboxSend(mailbox, msgType, data, len);
+
+        const Montauk::WinEvent* incoming = (const Montauk::WinEvent*)data;
+        if (incoming->type != 1 || incoming->mouse.scroll != 0)
+            return MailboxSend(mailbox, msgType, data, len);
+
+        bool incomingTransition = incoming->mouse.buttons != incoming->mouse.prev_buttons;
+        if (incomingTransition)
+            return MailboxSend(mailbox, msgType, data, len);
+
+        mailbox->lock.Acquire();
+        if (mailbox->receiverRefs == 0) {
+            mailbox->lock.Release();
+            return -1;
+        }
+
+        if (mailbox->count > 0) {
+            uint32_t idx = (mailbox->head + MaxMailboxMessages - 1) % MaxMailboxMessages;
+            MailboxMessage& latest = mailbox->messages[idx];
+            if (latest.type == msgType && latest.size == len && !latest.hasAttachment) {
+                const Montauk::WinEvent* queued = (const Montauk::WinEvent*)latest.data;
+                bool queuedTransition = queued->type != 1 ||
+                                        queued->mouse.scroll != 0 ||
+                                        queued->mouse.buttons != queued->mouse.prev_buttons;
+                if (!queuedTransition) {
+                    memcpy(latest.data, data, len);
+                    mailbox->lock.Release();
+                    NotifyObjectChanged((Object*)mailbox);
+                    return len;
+                }
+            }
+        }
+        mailbox->lock.Release();
+
+        return MailboxSend(mailbox, msgType, data, len);
+    }
+
     static int MailboxRecvInternal(Mailbox* mailbox, int receiverSlot, uint32_t* msgType,
                                    void* data, uint16_t* inOutLen, int* outAttachHandle,
                                    bool /*nonBlocking*/) {

kernel/src/Ipc/Ipc.hpp

@@ -98,6 +98,7 @@ namespace Ipc {
     void RetainMailbox(Mailbox* mailbox, bool sender, bool receiver);
     void ReleaseMailbox(Mailbox* mailbox, bool sender, bool receiver);
     int MailboxSend(Mailbox* mailbox, uint32_t msgType, const void* data, uint16_t len);
+    int MailboxSendCoalescedMouse(Mailbox* mailbox, uint32_t msgType, const void* data, uint16_t len);
     int MailboxRecv(Mailbox* mailbox, uint32_t* msgType, void* data, uint16_t* inOutLen, bool nonBlocking);
     int MailboxSendHandle(int handle, uint32_t msgType, const void* data, uint16_t len, int attachHandle);
     int MailboxRecvHandle(int handle, uint32_t* msgType, void* data, uint16_t* inOutLen, int* outAttachHandle);